212 results on '"Peter C. M. Christianen"'
Search Results
2. Phase-transition-induced jumping, bending, and wriggling of single crystal nanofibers of coronene
- Author
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Ken Takazawa, Jun-ichi Inoue, Kazutaka Mitsuishi, Yukihiro Yoshida, Hideo Kishida, Paul Tinnemans, Hans Engelkamp, and Peter C. M. Christianen
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Medicine ,Science - Abstract
Abstract For decades, it has been reported that some organic crystals suddenly crack, break, or jump when they are heated from room temperature. Recently, such crystals have been intensively studied both in fundamental science and for high-speed mechanical device applications. According to these studies, the sudden crystal motions have been attributed to structural phase transitions induced by heating. Stress created by the phase transition is released through the sudden and rapid motion of the crystals. Here we report that single crystal nanofibers of coronene exhibit a new type of ultrafast motion when they are cooled from room temperature and subsequently heated to room temperature. The nanofibers make centimeter-scale jumps accompanied by surprisingly unique behaviors such as sharp bending and wriggling. We found that the motions are caused by a significantly fast structural phase transition between two polymorphs of coronene. A theoretical investigation revealed that the sudden force generated by the phase transition together with the nanoscale dimensions and elastic properties create dynamical instability in the nanofibers that results in the motions. Our finding demonstrates the novel mechanism that leads to ultrafast, large deformation of organic crystals. more...
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- 2021
- Full Text
- View/download PDF
Catalog
3. High-Field Raman Scattering in an Antiferromagnet Fe3BO6
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Mikhail A. Prosnikov, Sergei N. Barilo, Nadzeya A. Liubochko, Roman V. Pisarev, and Peter C. M. Christianen
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antiferromagnet ,weak ferromagnetism ,Fe3BO6 ,high magnetic field ,Raman scattering ,lattice dynamics ,Chemistry ,QD1-999 - Abstract
The detailed Raman scattering investigation of the lattice and spin dynamics of a single crystal of the Fe3BO6 antiferromagnet is reported. Azimuthally resolved polarization measurements provided an unambiguous determination of the symmetry of observed excitations. Low-temperature experiments at T=4.2 K allowed us to reduce anharmonic contribution and deconvolute several overlapping phonon modes. Low-frequency measurements have made it possible to find two excitations at 13.1 and 16.6 cm−1, which were assigned to quasi-ferromagnetic and quasi-antiferromagnetic magnon excitations, respectively. The magnetic field applied along the hard-magnetization axis causes energy shifts of these excitations, but no spin-flip transition was observed up to B=30 T. more...
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- 2022
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4. Giant magnetic splitting inducing near-unity valley polarization in van der Waals heterostructures
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Philipp Nagler, Mariana V. Ballottin, Anatolie A. Mitioglu, Fabian Mooshammer, Nicola Paradiso, Christoph Strunk, Rupert Huber, Alexey Chernikov, Peter C. M. Christianen, Christian Schüller, and Tobias Korn more...
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Science - Abstract
In transition metal dichalcogenide monolayers, the spin and valley degrees of freedom are strongly coupled. Here, the authors engineer a WSe2/MoSe2 heterostructure in which inter-valley transitions of interlayer excitons exhibit a giant splitting and near-unity polarization in a magnetic field. more...
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- 2017
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5. An unforeseen polymorph of coronene by the application of magnetic fields during crystal growth
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Jason Potticary, Lui R. Terry, Christopher Bell, Alexandros N. Papanikolopoulos, Peter C. M. Christianen, Hans Engelkamp, Andrew M. Collins, Claudio Fontanesi, Gabriele Kociok-Köhn, Simon Crampin, Enrico Da Como, and Simon R. Hall more...
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Science - Abstract
Polymorphism, the presence of different crystal structures of the same molecular system, provides an opportunity to discover new phenomena and properties. Here, the authors crystallize coronene in the presence of a magnetic field, forming a different polymorph, which remains stable under ambient conditions. more...
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- 2016
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6. Strain-Induced Exciton Hybridization in WS2 Monolayers Unveiled by Zeeman-Splitting Measurements
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Elena Blundo, Paulo E. Faria Junior, Alessandro Surrente, Giorgio Pettinari, Mikhail A. Prosnikov, Katarzyna Olkowska-Pucko, Klaus Zollner, Tomasz Woźniak, Andrey Chaves, Tomasz Kazimierczuk, Marco Felici, Adam Babiński, Maciej R. Molas, Peter C. M. Christianen, Jaroslav Fabian, and Antonio Polimeni more...
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General Physics and Astronomy - Published
- 2022
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7. Phase-transition-induced jumping, bending, and wriggling of single crystal nanofibers of coronene
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Hans Engelkamp, Peter C. M. Christianen, Jun-ichi Inoue, Ken Takazawa, Hideo Kishida, Yukihiro Yoshida, Paul Tinnemans, and Kazutaka Mitsuishi
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Phase transition ,Materials science ,Chemical physics ,Science ,Physics::Optics ,Solid State Chemistry ,Bending ,010402 general chemistry ,01 natural sciences ,Article ,Crystal ,Stress (mechanics) ,chemistry.chemical_compound ,Soft Condensed Matter and Nanomaterials ,Multidisciplinary ,Nanowires ,010405 organic chemistry ,Coronene ,0104 chemical sciences ,chemistry ,Nanofiber ,Medicine ,Ultrashort pulse ,Single crystal - Abstract
For decades, it has been reported that some organic crystals suddenly crack, break, or jump when they are heated from room temperature. Recently, such crystals have been intensively studied both in fundamental science and for high-speed mechanical device applications. According to these studies, the sudden crystal motions have been attributed to structural phase transitions induced by heating. Stress created by the phase transition is released through the sudden and rapid motion of the crystals. Here we report that single crystal nanofibers of coronene exhibit a new type of ultrafast motion when they are cooled from room temperature and subsequently heated to room temperature. The nanofibers make centimeter-scale jumps accompanied by surprisingly unique behaviors such as sharp bending and wriggling. We found that the motions are caused by a significantly fast structural phase transition between two polymorphs of coronene. A theoretical investigation revealed that the sudden force generated by the phase transition together with the nanoscale dimensions and elastic properties create dynamical instability in the nanofibers that results in the motions. Our finding demonstrates the novel mechanism that leads to ultrafast, large deformation of organic crystals. more...
- Published
- 2021
8. Revealing Excitonic Complexes in Monolayer WS2 on Talc Dielectric
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Gabriela Augusta Prando, Marion E. Severijnen, Ingrid D. Barcelos, Uli Zeitler, Peter C. M. Christianen, Freddie Withers, and Yara Galvão Gobato
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Soft Condensed Matter and Nanomaterials ,General Physics and Astronomy ,Semiconductors and Nanostructures - Abstract
Contains fulltext : 244692.pdf (Publisher’s version ) (Open Access)
- Published
- 2021
9. Biofabrication of a Functional Tubular Construct from Tissue Spheroids Using Magnetoacoustic Levitational Directed Assembly
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Vladislav A. Parfenov, P. A. Karalkin, Elena A. Bulanova, Vladimir Mironov, Elizaveta V. Koudan, Oleg A. Sapozhnikov, E. A. Annenkova, Peter C. M. Christianen, Elizaveta K. Nezhurina, Peter M. van der Kraan, Alisa A. Krokhmal, Vladimir Kasyanov, A. A. Gryadunova, Yusef D. Khesuani, Egbert Oosterwijk, Hans Engelkamp, Stanislav V. Petrov, S.J.C. Granneman, Henk M. van Beuningen, F. D. A. S. Pereira, Sergey A. Tsysar, and Kaizheng Liu more...
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Materials science ,Human bladder ,Biomedical Engineering ,Pharmaceutical Science ,Biocompatible Materials ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Biomaterial scaffold ,Biomaterials ,All institutes and research themes of the Radboud University Medical Center ,Tissue engineering ,Smooth muscle ,Soft Condensed Matter and Nanomaterials ,Spheroids, Cellular ,Urological cancers Radboud Institute for Molecular Life Sciences [Radboudumc 15] ,Spectroscopy and Catalysis ,Humans ,Volume concentration ,Acoustic field ,Tissue Engineering ,Tissue Scaffolds ,Molecular Materials ,Spheroid ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Magnetic Fields ,0210 nano-technology ,Inflammatory diseases Radboud Institute for Molecular Life Sciences [Radboudumc 5] ,Biofabrication ,Biomedical engineering ,Biotechnology - Abstract
In traditional tissue engineering, synthetic or natural scaffolds are usually used as removable temporal support, which involves some biotechnology limitations. The concept of "scaffield" approach utilizing the physical fields instead of biomaterial scaffold has been proposed recently. In particular, a combination of intense magnetic and acoustic fields can enable rapid levitational bioassembly of complex-shaped 3D tissue constructs from tissue spheroids at low concentration of paramagnetic agent (gadolinium salt) in the medium. In the current study, the tissue spheroids from human bladder smooth muscle cells (myospheres) are used as building blocks for assembling the tubular 3D constructs. Levitational assembly is accomplished at low concentrations of gadolinium salts in the high magnetic field at 9.5 T. The biofabricated smooth muscle constructs demonstrate contraction after the addition of vasoconstrictive agent endothelin-1. Thus, hybrid magnetoacoustic levitational bioassembly is considered as a new technology platform in the emerging field of formative biofabrication. This novel technology of scaffold-free, nozzle-free, and label-free bioassembly opens a unique opportunity for rapid biofabrication of 3D tissue and organ constructs with complex geometry. more...
- Published
- 2020
10. Bright Exciton Fine-Structure in Two-Dimensional Lead Halide Perovskites
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Weibo Gao, M. A. Prosnikov, Dong Zhang, Qihua Xiong, Andrés Granados del Águila, Jun Xing, Sheng Liu, Peter C. M. Christianen, Kai Chang, Thong T. Do, and School of Physical and Mathematical Sciences
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Materials science ,Field (physics) ,Exciton ,Halide ,Bioengineering ,02 engineering and technology ,2D Lead Halide Perovskites ,Condensed Matter::Materials Science ,Lead (geology) ,Soft Condensed Matter and Nanomaterials ,Physics [Science] ,General Materials Science ,Spectroscopy ,Exciton Fine-Structure ,Condensed matter physics ,Condensed Matter::Other ,business.industry ,Mechanical Engineering ,Exchange interaction ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Magnetic field ,Semiconductor ,0210 nano-technology ,business - Abstract
The fast-growing field of atomically thin semiconductors urges a new understanding of two-dimensional excitons, which entirely determine their optical responses. Here, taking layered lead halide perovskites as an example of unconventional two-dimensional semiconductors, by means of versatile optical spectroscopy measurements, we resolve fine-structure splitting of bright excitons of up to ∼2 meV, which is among the largest values in two-dimensional semiconducting systems. The large fine-structure splitting is attributed to the strong electron-hole exchange interaction in layered perovskites, which is proven by the optical emission in high magnetic fields of up to 30 T. Furthermore, we determine the g-factors for these bright excitons as ∼+1.8. Our findings suggest layered lead halide perovskites are an ideal platform for studying exciton spin-physics in atomically thin semiconductors that will pave the way toward exciton manipulation for novel device applications. Ministry of Education (MOE) National Research Foundation (NRF) Q.X. acknowledges the support from the Singapore National Research Foundation through the NRF Investigatorship Award (NRF-NRFI2015-03) and the Singapore Ministry of Education via AcRF Tier 3 Programme “Geometrical Quantum Materials” (MOE2018-T3-1-002), Tier 2 Grant (MOE2018- T2-2-068) and Tier 1 Grants (RG103/15 and RG113/16). W.B.G. acknowledges the support from the Singapore National Research Foundation through a Singapore 2015 NRF fellowship Grant (NRF-NRFF2015-03). D.Z. and K.C. acknowledge the support from the MOST of China Grant (2017YFA0303400) and NSFC Grant (11434010). We acknowledge the support from HFML-RU/FOM, a member of the European Magnetic Field Laboratory (EMFL). A.G.D.A gratefully acknowledges the financial support of the Presidential Postdoctoral Fellowship program of the Nanyang Technological University. We acknowledge Dr. Xinxiong Li for his help on the single-crystal XRD characterization, and acknowledge Dr. Yuqing Huang and Dr. Chee Fai Fong for their help during the optical absorption measurements. more...
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- 2020
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11. Signature of Ultrafast Formation and Annihilation of Polaronic States in a Layered Ferromagnet
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Tingting Yin, Jing-Yang You, Yuqing Huang, Ha Thi Thu Do, Mikail A. Prosnikov, Weijie Zhao, Marco Serra, Peter C. M. Christianen, Zdenek Sofer, Handong Sun, Yuan Ping Feng, Qihua Xiong, and School of Physical and Mathematical Sciences more...
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Ultrafast ,Soft Condensed Matter and Nanomaterials ,Physics [Science] ,Mechanical Engineering ,General Materials Science ,Bioengineering ,Polaron ,General Chemistry ,Condensed Matter Physics - Abstract
The strong interaction between charge and lattice vibration gives rise to a polaron, which has a profound effect on optical and transport properties of matters. In magnetic materials, polarons are involved in spin dependent transport, which can be potentially tailored for spintronic and opto-spintronic device applications. Here, we identify the signature of ultrafast formation of polaronic states in CrBr3. The polaronic states are long-lived, having a lifetime on the time scale of nanoseconds to microseconds, which coincides with the emission lifetime of ∼4.3 μs. Transition of the polaronic states is strongly screened by the phonon, generating a redshift of the transition energy ∼0.2 eV. Moreover, energy-dependent localization of polaronic states is discovered followed by transport/annihilation properties. These results shed light on the nature of the polarons and their formation and transport dynamics in layered magnetic materials, which paves the way for the rational design of two-dimensional magnetic devices. Ministry of Education (MOE) National Research Foundation (NRF) Published version H.S. and T.Y. acknowledge the support from the Singapore National Research Foundation via Competitive Research Programme (NRF-CRP21-2018-0007 and NRF-CRP23-2019-0007). Y.H. acknowledges financial support from the Knut and Alice Wallenberg Foundation (KAW). Z.S. is supported by project LTAUSA19034 from Ministry of Education Youth and Sports (MEYS). J.Y. and Y.F. are supported by the Ministry of Education, Singapore, under its MOE AcRF Tier 3 Award MOE2018-T3-1-002. more...
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- 2022
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12. Valley-magnetophonon resonance for interlayer excitons
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Dmitry S Smirnov, Johannes Holler, Michael Kempf, Jonas Zipfel, Philipp Nagler, Mariana V Ballottin, Anatolie A Mitioglu, Alexey Chernikov, Peter C M Christianen, Christian Schüller, and Tobias Korn
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Mechanical Engineering ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Correlated Electron Systems ,General Chemistry ,Condensed Matter Physics ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter::Materials Science ,Soft Condensed Matter and Nanomaterials ,Mechanics of Materials ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,General Materials Science - Abstract
Heterobilayers consisting of MoSe$_2$ and WSe$_2$ monolayers can host optically bright interlayer excitons with intriguing properties such as ultralong lifetimes and pronounced circular polarization of their photoluminescence due to valley polarization, which can be induced by circularly polarized excitation or applied magnetic fields. Here, we report on the observation of an intrinsic valley-magnetophonon resonance for localized interlayer excitons promoted by invervalley hole scattering. It leads to a resonant increase of the photoluminescence polarization degree at the same field of 24.2 Tesla for H-type and R-type stacking configurations despite their vastly different excitonic energy splittings. As a microscopic mechanism of the hole intervalley scattering we identify the scattering with chiral TA phonons of MoSe$_2$ between excitonic states mixed by the long-range electron hole exchange interaction., Comment: 7+5 pages, 2+0 figures more...
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- 2022
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13. Massive Magnetostriction of the Paramagnetic Insulator KEr(MoO4)(2) via a Single-Ion Effect
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Bence Bernáth, Khrystyna Kutko, Steffen Wiedmann, Olga Young, Hans Engelkamp, Peter C. M. Christianen, Sergii Poperezhai, Leonid V. Pourovskii, Sergii Khmelevskyi, and Dmytro Kamenskyi
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Soft Condensed Matter & Nanomaterials (HFML) ,Soft Condensed Matter and Nanomaterials ,0103 physical sciences ,ddc:530 ,Semiconductors and Nanostructures ,02 engineering and technology ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,021001 nanoscience & nanotechnology ,010306 general physics ,0210 nano-technology ,01 natural sciences ,Electronic, Optical and Magnetic Materials - Abstract
Contains fulltext : 247942.pdf (Publisher’s version ) (Open Access)
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- 2022
14. Nonlinear Terahertz transmission spectroscopy on Ga-doped germanium in high magnetic fields
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Bence Bernáth, Papori Gogoi, Andrea Marchese, Dmytro Kamenskyi, Hans Engelkamp, Denis Arslanov, Britta Redlich, Peter C. M. Christianen, and Jan C. Maan
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FELIX Condensed Matter Physics ,Soft Condensed Matter & Nanomaterials (HFML) ,Soft Condensed Matter and Nanomaterials ,Correlated Electron Systems ,ddc:530 ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,FELIX Infrared and Terahertz Spectroscopy - Abstract
Contains fulltext : 251300.pdf (Publisher’s version ) (Open Access)
- Published
- 2022
15. Strain-Induced Exciton Hybridization in WS_{2} Monolayers Unveiled by Zeeman-Splitting Measurements
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Elena, Blundo, Paulo E Faria, Junior, Alessandro, Surrente, Giorgio, Pettinari, Mikhail A, Prosnikov, Katarzyna, Olkowska-Pucko, Klaus, Zollner, Tomasz, Woźniak, Andrey, Chaves, Tomasz, Kazimierczuk, Marco, Felici, Adam, Babiński, Maciej R, Molas, Peter C M, Christianen, Jaroslav, Fabian, and Antonio, Polimeni more...
- Abstract
Mechanical deformations and ensuing strain are routinely exploited to tune the band gap energy and to enhance the functionalities of two-dimensional crystals. In this Letter, we show that strain leads also to a strong modification of the exciton magnetic moment in WS_{2} monolayers. Zeeman-splitting measurements under magnetic fields up to 28.5 T were performed on single, one-layer-thick WS_{2} microbubbles. The strain of the bubbles causes a hybridization of k-space direct and indirect excitons resulting in a sizable decrease in the modulus of the g factor of the ground-state exciton. These findings indicate that strain may have major effects on the way the valley number of excitons can be used to process binary information in two-dimensional crystals. more...
- Published
- 2021
16. Interlayer exciton valley polarization dynamics in large magnetic fields
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Johannes Holler, Malte Selig, Michael Kempf, Jonas Zipfel, Philipp Nagler, Manuel Katzer, Florian Katsch, Mariana V. Ballottin, Anatolie A. Mitioglu, Alexey Chernikov, Peter C. M. Christianen, Christian Schüller, Andreas Knorr, and Tobias Korn more...
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Soft Condensed Matter & Nanomaterials (HFML) ,Soft Condensed Matter and Nanomaterials ,Condensed Matter - Mesoscale and Nanoscale Physics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,FOS: Physical sciences ,Correlated Electron Systems - Abstract
In van der Waals heterostructures (HS) consisting of stacked MoSe$_2$ and WSe$_2$ monolayers, optically bright interlayer excitons (ILE) can be observed when the constituent layers are crystallographically aligned. The symmetry of the monolayers allows for two different types of alignment, in which the momentum-direct interlayer transitions are either valley-conserving (R-type alignment) or changing the valley index (H-type anti-alignment). Here, we study the valley polarization dynamics of ILE in magnetic fields up to 30~Tesla by time-resolved photoluminescence (PL). For all ILE types, we find a finite initial PL circular degree of polarization ($DoP$) after unpolarized excitation in applied magnetic fields. For ILE in H-type HS, we observe a systematic increase of the PL $DoP$ with time in applied magnetic fields, which saturates at values close to unity for the largest fields. By contrast, for ILE in R-type HS, the PL $DoP$ shows a decrease and a zero crossing before saturating with opposite polarization. This unintuitive behavior can be explained by a model considering the different ILE states in H- and R-type HS and their selection rules coupling PL helicity and valley polarization. more...
- Published
- 2021
17. Bright and dark excitons in two-dimensional perovskite semiconductors
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Peter C. M. Christianen, Kai Chang, Andrés Granados del Águila, Weibo Gao, Qihua Xiong, Sheng Liu, Dong Zhang, Jun Xing, Thu Ha Do, and M. A. Prosnikov
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Physics ,Condensed Matter::Other ,business.industry ,Astrophysics::High Energy Astrophysical Phenomena ,Exciton ,Exchange interaction ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Molecular physics ,Magnetic field ,Condensed Matter::Materials Science ,Dipole ,Semiconductor ,Optical emission spectroscopy ,business ,Recombination ,Perovskite (structure) - Abstract
Lead halide perovskites are known for their great potential in high-performance light-harvesting devices. We investigated the exciton recombination properties of 2D perovskites. We resolved two bright (optically allowed) exciton doublets and a dark (optically forbidden) exciton. Particularly, under the inherently strong electron-hole exchange interaction, each bright exciton doublet is split into two orthogonally orienting dipoles with large energy splitting of 2 meV, which is the largest experimental values in two-dimensional semiconductors. Furthermore, we observed an efficient transfer of oscillator strengths from the bright excitons to a dark exciton, which originates from strong spin-mixing between bright and dark excitons induced by external magnetic fields, and the optical emission from the dark exciton is brightened. Our results reveal that the physics on exciton recombination in 2D perovskites is rich, while the optical emission properties can be manipulated by external fields more...
- Published
- 2021
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18. Direct Observation of Magnon-Phonon Strong Coupling in Two-Dimensional Antiferromagnet at High Magnetic Fields
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M. A. Prosnikov, David Sedmidubský, Qihua Xiong, Sheng Liu, Pinaki Sengupta, Chee Kwan Gan, Thong T. Do, Dhiman Bhowmick, Peter C. M. Christianen, Andrés Granados del Águila, Zdenek Sofer, and School of Physical and Mathematical Sciences more...
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Physics ,Zeeman effect ,Condensed matter physics ,Phonon ,Magnon ,General Physics and Astronomy ,Magnetic lattice ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Magnetic field ,Scattering ,Condensed Matter::Materials Science ,symbols.namesake ,Soft Condensed Matter and Nanomaterials ,Physics [Science] ,Condensed Matter::Superconductivity ,Quasiparticle ,symbols ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,Spin (physics) ,Spin-Waves - Abstract
We report the direct observation of strong coupling between magnons and phonons in a two-dimensional antiferromagnetic semiconductor FePS_{3}, via magneto-Raman spectroscopy at magnetic fields up to 30 Tesla. A Raman-active magnon at 121 cm^{-1} is identified through Zeeman splitting in an applied magnetic field. At a field-driven resonance with a nearby phonon mode, a hybridized magnon-phonon quasiparticle is formed due to strong coupling between the two modes. We develop a microscopic model of the strong coupling in the two-dimensional magnetic lattice, which enables us to elucidate the nature of the emergent quasiparticle. Our polarized Raman results directly show that the magnons transfer their spin angular momentum to the phonons and generate phonon spin through the strong coupling. Ministry of Education (MOE) Nanyang Technological University Published version This work is mainly supported by the Singapore Ministry of Education via AcRF Tier 3 Programme “Geometrical Quantum Material” (MOE2018-T3-1-002). Q. X. acknowledges strong support from the State Key Laboratory of Low-Dimensional Quantum Physics and the start-up grant from Tsinghua University. P. S. acknowledges financial support from the Ministry of Education, Singapore, through Grant No. MOE2019-T2-2-119. A. G. D. A. gratefully acknowledges the financial support from the Presidential Postdoctoral Fellowship program of the Nanyang Technological University Singapore. Z. S. was supported by project LTAUSA19034 from Ministry of Education Youth and Sports (MEYS). more...
- Published
- 2021
19. Electrical and optical properties of transition metal dichalcogenides on talc dielectrics
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Shi Guo, Ingrid D. Barcelos, Peter C. M. Christianen, Uli Zeitler, Freddie Withers, Gabriela A. Prando, Yara Galvão Gobato, Marion Severijnen, and Darren Nutting
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Materials science ,Photoluminescence ,business.industry ,Heterojunction ,Substrate (electronics) ,Dielectric ,Talc ,symbols.namesake ,Hysteresis ,Soft Condensed Matter and Nanomaterials ,Monolayer ,symbols ,medicine ,Optoelectronics ,General Materials Science ,Semiconductors and Nanostructures ,van der Waals force ,business ,medicine.drug - Abstract
Advanced van der Waals (vdW) heterostructure devices rely on the incorporation of high quality dielectric materials which need to possess a low defect density as well as being atomically smooth and uniform. In this work we explore the use of talc dielectrics as a potentially clean alternative substrate to hexagonal boron nitride (hBN) for few-layer transition metal dichalcogenide (TMDC) transistors and excitonic TMDC monolayers. We find that talc dielectric transistors show small hysteresis which does not depend strongly on sweep rate and show negligible leakage current for our studied dielectric thicknesses. We also show narrow photoluminescence linewidths down to 10 meV for different TMDC monolayers on talc which highlights that talc is a promising material for future van der Waals devices. more...
- Published
- 2021
20. Synthesis and Magnetic Properties of Two-Step-Coordination Schiff Base Clusters
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Peter C. M. Christianen, Uli Zeitler, Paul Tinnemans, J.C. Maan, Hans Engelkamp, Alan E. Rowan, and Laurens Peters
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chemistry.chemical_classification ,Soft Condensed Matter & Nanomaterials (HFML) ,Schiff base ,Chemistry ,Molecular Materials ,chemistry.chemical_element ,Crystal structure ,Manganese ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,Solid State Chemistry ,Coordination complex ,Inorganic Chemistry ,Paramagnetism ,chemistry.chemical_compound ,Crystallography ,Transition metal ,Soft Condensed Matter and Nanomaterials ,Cluster (physics) ,Semiconductors and Nanostructures ,Pincer ligand - Abstract
A new family of paramagnetic coordination compounds based on a diimine-pyridine pincer ligand has been prepared, using a two-step synthetic approach. The sequential introduction of identical or different transition metals (Co, Mn, Ni, Zn) afforded mono-, di-, tri- and tetranuclear clusters, whose crystal structure has been determined. Magnetic studies reveal that the metals within the trinuclear manganese cluster engage in a small ferromagnetic exchange interaction (J=0.15 K). These studies enable the design of new clusters with specific magnetic properties. more...
- Published
- 2021
21. Polarized emission of CdSe nanocrystals in magnetic field: the role of phonon-assisted recombination of the dark exciton
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Gang Qiang, A. A. Golovatenko, Aleksei A. Onushchenko, Anna V. Rodina, M. A. Prosnikov, Victor F. Sapega, Peter C. M. Christianen, Dmitri R. Yakovlev, E. A. Zhukov, Vadim Kh Kaibyshev, Elena V. Shornikova, I. V. Kalitukha, and Manfred Bayer more...
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education.field_of_study ,Zeeman effect ,Photoluminescence ,Materials science ,Condensed matter physics ,Spin polarization ,Condensed Matter::Other ,Phonon ,Exciton ,Population ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Polarization (waves) ,Magnetic field ,Condensed Matter::Materials Science ,symbols.namesake ,Soft Condensed Matter and Nanomaterials ,symbols ,General Materials Science ,education - Abstract
The recombination dynamics and spin polarization of excitons in CdSe nanocrystals synthesized in a glass matrix are investigated using polarized photoluminescence in high magnetic fields up to 30 Tesla. The dynamics are accelerated by increasing temperature and magnetic field, confirming the dark exciton nature of low-temperature photoluminescence (PL). The circularly polarized PL in magnetic fields reveals several unusual appearances: (i) a spectral dependence of the polarization degree, (ii) its low saturation value, and (iii) a stronger intensity of the Zeeman component which is higher in energy. The latter feature is the most surprising being in contradiction with the thermal population of the exciton spin sublevels. The same contradiction was previously observed in the ensemble of wet-chemically synthesized CdSe nanocrystals but was not understood. We present a theory which explains all the observed features and shows that the inverted ordering of the circularly polarized PL maxima from the ensemble of nanocrystals is a result of competition between the zero phonon (ZPL) and one optical phonon-assisted (1PL) emission of the dark excitons. The essential aspects of the theoretical model are different polarization properties of the dark exciton emission via ZPL and 1PL recombination channels and the inhomogeneous broadening of the PL spectrum from the ensemble of nanocrystals exceeding the optical phonon energy. more...
- Published
- 2020
22. Hole and electron effective masses in single InP nanowires with a Wurtzite-Zincblende homojunction
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Elena Blundo, Peter C. M. Christianen, Andrés Granados del Águila, Antonio Polimeni, Chennupati Jagadish, Yanan Guo, Marta De Luca, Davide Tedeschi, Hark Hoe Tan, and H. Aruni Fonseka
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Soft Condensed Matter & Nanomaterials (HFML) ,Materials science ,excitons ,Exciton ,TK ,Nanowire ,General Physics and Astronomy ,02 engineering and technology ,Electron ,Light hole ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,Soft Condensed Matter and Nanomaterials ,Phase (matter) ,General Materials Science ,InP nanowires ,Homojunction ,light hole ,QC ,Wurtzite crystal structure ,business.industry ,carrier effective mass ,crystal-phase homostructures ,General Engineering ,magneto-photoluminescence ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,wurtzite and zincblende ,Optoelectronics ,0210 nano-technology ,business - Abstract
The formation of wurtzite (WZ) phase in III–V nanowires (NWs) such as GaAs and InP is a complication hindering the growth of pure-phase NWs, but it can also be exploited to form NW homostructures consisting of alternate zincblende (ZB) and WZ segments. This leads to different forms of nanostructures, such as crystal-phase superlattices and quantum dots. Here, we investigate the electronic properties of the simplest, yet challenging, of such homostructures: InP NWs with a single homojunction between pure ZB and WZ segments. Polarization-resolved microphotoluminescence (μ-PL) measurements on single NWs provide a tool to gain insights into the interplay between NW geometry and crystal phase. We also exploit this homostructure to simultaneously measure effective masses of charge carriers and excitons in ZB and WZ InP NWs, reliably. Magneto-μ-PL measurements carried out on individual NWs up to 29 T at 77 K allow us to determine the free exciton reduced masses of the ZB and WZ crystal phases, showing the heavier character of the WZ phase, and to deduce the effective mass of electrons in ZB InP NWs (me= 0.080 m0). Finally, we obtain the reduced mass of light-hole excitons in WZ InP by probing the second optically permitted transition Γ7C ↔ Γ7uV with magneto-μ-PL measurements carried out at room temperature. This information is used to extract the experimental light-hole effective mass in WZ InP, which is found to be mlh = 0.26 m0, a value much smaller than the one of the heavy hole mass. Besides being a valuable test for band structure calculations, the knowledge of carrier masses in WZ and ZB InP is important in view of the optimization of the efficiency of solar cells, which is one of the main applications of InP NWs.\ud \ud more...
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- 2020
23. Peculiar Circularly Polarized Photoluminescence of CdSe Nanocrystals: the Role of Optical Phonons
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Alexey Onushchenko, Dmitri R. Yakovlev, Gang Qiang, Manfred Bayer, Peter C. M. Christianen, A. A. Golovatenko, M. A. Prosnikov, Anna V. Rodina, and Elena V. Shornikova
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Photoluminescence ,Materials science ,Cdse nanocrystals ,Phonon ,business.industry ,Optoelectronics ,business - Published
- 2020
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24. Exciton-phonon coupling in InP quantum dots with ZnS and (Zn,Cd)Se shells
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Mariana V. Ballottin, Jonathan Buhot, Annalisa Brodu, Daniel Vanmaekelbergh, Dorian Dupont, Freddy T. Rabouw, Mickael D. Tessier, Celso de Mello Donegá, Zeger Hens, and Peter C. M. Christianen
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Photoluminescence ,Phonon ,Exciton ,02 engineering and technology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Coupling (probability) ,01 natural sciences ,Molecular physics ,Condensed Matter::Materials Science ,Dark state ,Quantum dot ,0103 physical sciences ,Content (measure theory) ,Spontaneous emission ,010306 general physics ,0210 nano-technology - Abstract
InP-based colloidal quantum dots are promising for optoelectronic devices such as light-emitting diodes and lasers. Understanding and optimizing their emission process is of scientific interest and essential for large-scale applications. Here we present a study of the exciton recombination dynamics in InP QDs with various shells: ZnS, ZnSe, and (Zn,Cd)Se with different amounts of Cd (5, 9, 12%). Phonon energies extracted from Raman spectroscopy measurements at cryogenic temperatures (4--5 K) are compared with exciton emission peaks observed in fluorescence line narrowing spectra. This allowed us to determine the position of both the bright $F=\ifmmode\pm\else\textpm\fi{}1$ state and the lowest dark $F=\ifmmode\pm\else\textpm\fi{}2$ state. We could identify the phonon modes involved in the radiative recombination of the dark state and found that acoustic and optical phonons of both the core and the shell are involved in this process. The Cd content in the shell increases electron wave-function delocalization, and thereby enhances the exciton-phonon coupling through the Fr\"ohlich interaction. more...
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- 2020
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25. Scaffold-free and label-free biofabrication technology using levitational assembly in a high magnetic field
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Elizaveta V. Koudan, Elizaveta K. Nezhurina, Lorenzo Moroni, Frederico Das Pereira, Vladimir Mironov, M. I. Myasnikov, Yusef D. Khesuani, Peter C. M. Christianen, Carlos Mota, Hans Engelkamp, P. A. Karalkin, Kenny A. van Kampen, Frank Walboomers, Stanislav V. Petrov, Vladislav A. Parfenov, Oleg F. Petrov, CTR, and RS: MERLN - Complex Tissue Regeneration (CTR) more...
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Bitter electromagnet ,Technology ,Materials science ,Magnetism ,Biomedical Engineering ,Bioengineering ,Biochemistry ,Cell Line ,Biomaterials ,Paramagnetism ,All institutes and research themes of the Radboud University Medical Center ,Soft Condensed Matter and Nanomaterials ,Humans ,Magnetic levitation ,high magnetic field ,magnetic levitation ,Tissue Engineering ,Tissue Scaffolds ,biofabrication ,General Medicine ,tissue spheroids ,Magnetic field ,Reconstructive and regenerative medicine Radboud Institute for Molecular Life Sciences [Radboudumc 10] ,Magnetic Fields ,Magnet ,CELLS ,Levitation ,gadolinium salt ,Biotechnology ,Biomedical engineering ,Biofabrication - Abstract
The feasibility of magnetic levitational bioassembly of tissue-engineered constructs from living tissue spheroids in the presence of paramagnetic ions (i.e. Gd3+) was recently demonstrated. However, Gd(3+)is relatively toxic at concentrations above 50 mM normally used to enable magnetic levitation with NdFeB-permanent magnets. Using a high magnetic field (a 50 mm-bore, 31 T Bitter magnet) at the High Field Magnet Laboratory at Radboud University in Nijmegen, The Netherlands, we performed magnetic levitational assembly of tissue constructs from living spheroids prepared from the SW1353 chondrosarcoma cell line at 0.8 mM Gd(3+)containing salt gadobutrol at 19 T magnetic field. The parameters of the levitation process were determined on the basis of polystyrene beads with a 170 mu m-diameter. To predict the theoretical possibility of assembly, a zone of stable levitation in the horizontal and vertical areas of cross sections was previously calculated. The construct from tissue spheroids partially fused after 3 h in levitation. The analysis of viability after prolonged exposure (1 h) to strong magnetic fields (up to 30 T) showed the absence of significant cytotoxicity or morphology changes in the tissue spheroids. A high magnetic field works as a temporal and removal support or so-called 'scaffield'. Thus, formative biofabrication of tissue-engineered constructs from tissue spheroids in the high magnetic field is a promising research direction more...
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- 2020
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26. Lattice dynamics and spontaneous magnetodielectric effect in ilmenite CoTiO$_3$
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Peter C. M. Christianen, A. M. Balbashov, N. N. Novikova, N. V. Siverin, Roman V. Pisarev, R. M. Dubrovin, V. A. Chernyshev, and M. A. Prosnikov
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Phonon ,Physics::Optics ,02 engineering and technology ,01 natural sciences ,Materials Chemistry ,Condensed Matter - Materials Science ,Condensed matter physics ,Metals and Alloys ,COBALT COMPOUNDS ,SINGLE CRYSTALS ,PHONONS ,021001 nanoscience & nanotechnology ,DFT CALCULATIONS ,MAGNETIC EXCITATIONS ,Magnetic field ,Mechanics of Materials ,RAMAN SPECTROSCOPY ,symbols ,INFRARED SPECTROSCOPY ,0210 nano-technology ,LATTICE DYNAMICS ,COTIO3 ,Materials science ,ZERO MAGNETIC FIELDS ,LATTICE VIBRATIONS ,DIELECTRIC SPECTROSCOPY ,Infrared spectroscopy ,FOS: Physical sciences ,PERMITTIVITY ,Dielectric ,ANTIFERROMAGNETIC ORDERING TEMPERATURE ,TITANIUM COMPOUNDS ,RAMAN-ACTIVE PHONON ,010402 general chemistry ,SPECTROSCOPIC TECHNIQUE ,symbols.namesake ,ANTIFERROMAGNETISM ,Soft Condensed Matter and Nanomaterials ,TECHNOLOGICAL APPLICATIONS ,Antiferromagnetism ,MAGNETO-DIELECTRIC EFFECTS ,Spins ,Mechanical Engineering ,ILMENITE ,Materials Science (cond-mat.mtrl-sci) ,0104 chemical sciences ,DIELECTRIC PERMITTIVITIES ,ELECTROMAGNETS ,Raman spectroscopy ,Single crystal - Abstract
Ilmenite-type crystals find a variety of technological applications due to their intriguing physical properties. We present the results of the lattice dynamics studies of honeycomb antiferromagnetic ilmenite CoTiO$_3$ single crystal by the complementary polarized infrared, Raman, and dielectric spectroscopic techniques that are supplemented by the DFT calculations. The frequencies and symmetries of all predicted infrared and Raman active phonons were uniquely identified. Furthermore, it was found that the dielectric permittivity demonstrates distinct changes below antiferromagnetic ordering temperature in zero magnetic field due to spontaneous magnetodielectric effect. Our results establish the reliable basis for further investigation of the coupling of phonons with spins, magnetic excitations and other physical phenomena of this promising material., Comment: 11 pages, 8 figures, 2 tables, 2 tables more...
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- 2020
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27. Electron and Hole g-Factors and Spin Dynamics of Negatively Charged Excitons in CdSe/CdS Colloidal Nanoplatelets with Thick Shells
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Yuri G. Kusrayev, Dmitri R. Yakovlev, M. A. Semina, Michel Nasilowski, Benoit Dubertret, V. F. Sapega, Mariana V. Ballottin, A. A. Golovatenko, Anatolie A. Mitioglu, Donghai Feng, Anna V. Rodina, Peter C. M. Christianen, Elena V. Shornikova, Nathan Flipo, Louis Biadala, Manfred Bayer, Experimentelle Physik 2, Technische Universität Dortmund [Dortmund] (TU), Rzhanov Institute of Semiconductor Physics (ISP), Siberian Branch of the Russian Academy of Sciences (SB RAS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Physique - IEMN (PHYSIQUE - IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), State Key Laboratory of Precision Spectroscopy, East China Normal University [Shangaï] (ECNU), High Field Magnet Laboratory (HFML-EMFL), Radboud University [Nijmegen], Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL), ACKNOWLEDGMENTSThe authors are thankful to Al. L. Efros for fruitful discussions.E.V.S., D.F., D.R.Y., A.V.R., M.A.S., A.A.G., and M.B.acknowledge support of the Deutsche Forschungsgemeinschaftin the frame of ICRC TRR 160. E.V.S., D.R.Y., V.F.S. andYu.G.K. acknowledge the Russian Science Foundation (GrantNo. 14-42-00015) for support of Raman experiments. Weacknowledge the support from HFML-RU/FOM, a member ofthe European Magnetic Field Laboratory (EMFL). B.D.acknowledges funding from the EU Marie Curie project642656 'Phonsi'., European Project: 642656,H2020,H2020-MSCA-ITN-2014,Phonsi(2015), and Physique-IEMN (PHYSIQUE-IEMN) more...
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Photoluminescence ,Exciton ,FOS: Physical sciences ,Correlated Electron Systems ,Bioengineering ,02 engineering and technology ,Electron ,spin dynamics ,010402 general chemistry ,01 natural sciences ,CdSe ,Condensed Matter::Materials Science ,symbols.namesake ,[SPI]Engineering Sciences [physics] ,Soft Condensed Matter and Nanomaterials ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Faraday effect ,core/shell nanocrystals ,General Materials Science ,Wurtzite crystal structure ,Physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Condensed Matter::Other ,business.industry ,Mechanical Engineering ,Nanoplatelets ,trion ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Semiconductor ,Quantum dot ,symbols ,Trion ,0210 nano-technology ,business - Abstract
International audience; We address spin properties and spin dynamics of carriers and charged excitons in CdSe/CdS colloidal nanoplatelets with thick shells. Magneto-optical studies are performed by time-resolved and polarization-resolved photoluminescence, spin-flip Raman scattering and picosecond pump-probe Faraday rotation in magnetic fields up to 30 T. We show that at low temperatures the nanoplatelets are negatively charged so that their photoluminescence is dominated by radiative recombination of negatively charged excitons (trions). Electron g-factor of 1.68 is measured, and heavy-hole g-factor varying with increasing magnetic field from -0.4 to -0.7 is evaluated. Hole g-factors for two-dimensional structures are calculated for various hole confining potentials for cubic- and wurtzite lattice in CdSe core. These calculations are extended for various quantum dots and nanoplatelets based on II-VI semiconductors. We developed a magneto-optical technique for the quantitative evaluation of the nanoplatelets orientation in ensemble. more...
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- 2018
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28. Correction to Addressing the Fundamental Electronic Properties of Wurtzite GaAs Nanowires by High-Field Magneto-Photoluminescence Spectroscopy
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Marta De Luca, Silvia Rubini, Marco Felici, Alan Meaney, Peter C. M. Christianen, Faustino Martelli, and Antonio Polimeni
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Mechanical Engineering ,General Materials Science ,Bioengineering ,General Chemistry ,Condensed Matter Physics - Published
- 2021
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29. Negatively Charged and Dark Excitons in CsPbBr3 Perovskite Nanocrystals Revealed by High Magnetic Fields
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Peter C. M. Christianen, Mariana V. Ballottin, Manfred Bayer, Dmitri R. Yakovlev, Emmanuel Lhuillier, Louis Biadala, Damien Canneson, Elena V. Shornikova, Tobias Rogge, Anatolie A. Mitioglu, Technische Universität Dortmund [Dortmund] (TU), Siberian Branch of the Russian Academy of Sciences (SB RAS), A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences [Moscow] (RAS), Radboud university [Nijmegen], Physico-chimie et dynamique des surfaces (INSP-E6), Institut des Nanosciences de Paris (INSP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Physique-IEMN (PHYSIQUE-IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), This work was supported by French state funds managed by the ANR within the Investissements d'Avenir programme under reference ANR-11-IDEX-0004-02, and more specifically within the framework of the Cluster of Excellence MATISSE., ANR-11-IDEX-0004,SUPER,Sorbonne Universités à Paris pour l'Enseignement et la Recherche(2011), Radboud University [Nijmegen], and Physique - IEMN (PHYSIQUE - IEMN) more...
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Soft Condensed Matter & Nanomaterials (HFML) ,Exciton ,perovskites ,chemistry.chemical_element ,Bioengineering ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,02 engineering and technology ,Electron ,010402 general chemistry ,01 natural sciences ,Condensed Matter::Materials Science ,General Materials Science ,Spectroscopy ,CsPbBr3 ,fine structure ,Biexciton ,Perovskite (structure) ,[PHYS]Physics [physics] ,Physics ,Mechanical Engineering ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Magnetic field ,chemistry ,Caesium ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Atomic physics ,Trion ,0210 nano-technology - Abstract
The optical properties of colloidal cesium lead halide perovskite (CsPbBr3) nanocrystals are examined by time-resolved and polarization-resolved spectroscopy in high magnetic fields up to 30 T. We unambiguously show that at cryogenic temperatures the emission is dominated by recombination of negatively charged excitons with radiative decay time of 300 ps. The additional long-lived emission, which decay time shortens from 40 down to 8 ns and in which the decay time shortens and relative amplitude increases in high magnetic fields, evidences the presence of a dark exciton. We evaluate g-factors of the bright exciton gX = +2.4, the electron ge = +2.18, and the hole gh = −0.22. more...
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- 2017
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30. Confining Potential as a Function of Polymer Stiffness and Concentration in Entangled Polymer Solutions
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Masoumeh Keshavarz, Jialiang Xu, Peter C. M. Christianen, Onno I. van den Boomen, Jan C. Maan, Alan E. Rowan, and Hans Engelkamp
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Soft Condensed Matter & Nanomaterials (HFML) ,Materials science ,Nanotechnology ,Polymer architecture ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,02 engineering and technology ,01 natural sciences ,Matrix (mathematics) ,Spectroscopy of Solids and Interfaces ,0103 physical sciences ,Materials Chemistry ,medicine ,Molecule ,Physical and Theoretical Chemistry ,010306 general physics ,Worm-like chain ,Persistence length ,chemistry.chemical_classification ,Quantitative Biology::Biomolecules ,Molecular Materials ,Stiffness ,Polymer ,021001 nanoscience & nanotechnology ,Surfaces, Coatings and Films ,Condensed Matter::Soft Condensed Matter ,chemistry ,Chemical physics ,Polymer physics ,medicine.symptom ,0210 nano-technology - Abstract
We directly track the tubelike motion of individual fluorescently labeled polymer molecules in a concentrated solution of unlabeled polymers. We use a single molecule wide-field fluorescence microscopy technique that is able to determine characteristic properties of the polymer dynamics, such as the confining potential, the tube diameter, and the Rouse time. The use of synthetic polymers allows us to investigate the confined motion of the polymer chains not only as a function of polymer concentration (mesh size) but also versus the persistence length of the matrix polymers. Although the polymers used have a persistence length much smaller than their contour length, our experimental results lead to a dependence of the tube diameter on both the mesh size and the persistence length, which follows the theoretically predicted relation for semiflexible chains. more...
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- 2017
31. Hyperfine Interactions and Slow Spin Dynamics in Quasi-isotropic InP-based Core/Shell Colloidal Nanocrystals
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Mariana V. Ballottin, Mickael D. Tessier, Daniel Vanmaekelbergh, Peter C. M. Christianen, Dorian Dupont, Dmitri R. Yakovlev, Zeger Hens, Celso de Mello Donegá, Damien Canneson, Manfred Bayer, Louis Biadala, Annalisa Brodu, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Universiteit Gent = Ghent University [Belgium] (UGENT), Radboud university [Nijmegen], Inorganic and Physical Chemistry, Debye Institute for Nanomaterials Science, Utrecht University [Utrecht], Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Physique-IEMN (PHYSIQUE-IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Sub Condensed Matter and Interfaces, Condensed Matter and Interfaces, Physics and Chemistry of Nanostructures, Universiteit Gent = Ghent University (UGENT), High Field Magnet Laboratory (HFML-EMFL), Radboud University [Nijmegen], Technische Universität Dortmund [Dortmund] (TU), Physique - IEMN (PHYSIQUE - IEMN), ACKNOWLEDGMENTSWe acknowledge the support from HFML-RU/FOM, amember of the European Magnetic Field Laboratory(EMFL). We acknowledge the financial support by theDeutsche Forschungsgemeinschaft in the frame of the ICRCTRR160 (project B1) and TRR142 (project B1) and by theGovernment of Russia (project number 14.Z50.31.0021,leading scientist M.B.). We acknowledge the support by theEuropean Commission via the Marie-Sklodowska Curie actionPhonsi (H2020-MSCA-ITN-642656). D.V. acknowledgesfunding by the ERC Advanced Grant 'FIRSTSTEP' 692691.Z.H. acknowledges support by SIM-Flanders (SBO-QDOCCO), FWO-Vlaanderen (Research Project 17006602), andGhent University (GOA 01G01019), and European Project: 642656,H2020,H2020-MSCA-ITN-2014,Phonsi(2015) more...
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Exciton ,General Physics and Astronomy ,Physics::Optics ,Correlated Electron Systems ,02 engineering and technology ,Electron ,010402 general chemistry ,01 natural sciences ,symbols.namesake ,Condensed Matter::Materials Science ,Soft Condensed Matter and Nanomaterials ,Taverne ,General Materials Science ,Spin (physics) ,III-V ,III−V ,Hyperfine structure ,[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics] ,Zeeman effect ,high magnetic field ,Magnetic moment ,Condensed matter physics ,Condensed Matter::Other ,General Engineering ,dark exciton ,021001 nanoscience & nanotechnology ,colloidal nanostructure ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,0104 chemical sciences ,Magnetic field ,hyperfine interaction ,Quantum dot ,symbols ,0210 nano-technology - Abstract
International audience; Colloidal InP core/sell nanocrystals are taking over CdSe-based nanocrystals, notably in optoelectronic applications. Despite their use in commercial device such as display screens, the optical properties of InP nanocrystals and especially their relation with the exciton fine structure remains poorly understood. In this work, we show that the magneto-optical properties of ensemble InP-based core/shell nanocrystals investigated in strong magnetic fields up to 30 T are strikingly different compared to other colloidal nanostructures. Notably, the mixing of the lowest spin-forbidden dark exciton state with the nearest spin-allowed bright state does not occur, up to the highest magnetic fields applied. This lack of mixing in ensemble of nanocrystals suggests an anisotropy-tolerance of InP nanocrystals. This striking property allowed us to unveil the slow spin dynamics between Zeeman sublevels (up to 400 ns at 15 T). Furthermore, we show that the unexpected magnetic field-induced lengthening of the dark exciton lifetime results from the hyperfine interaction between the spin of the electron in the dark exciton with the nuclear magnetic moments. Our results demonstrate the richness of the spin physics in InP quantum dots and stress the large potential of InP nanostructures for spin-based applications. KEYWORD: colloidal nanostructure, III-V, hyperfine interaction, dark exciton, high magnetic field more...
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- 2019
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32. Intervalley Scattering of Interlayer Excitons in a MoS2/MoSe2/MoS2 Heterostructure in High Magnetic Field
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Duncan K. Maude, Paulina Plochocka, Anatolie A. Mitioglu, Alessandro Surrente, Peter C. M. Christianen, Yen-Cheng Kung, Mariana V. Ballottin, Łukasz Kłopotowski, Dumitru Dumcenco, Michal Baranowski, Andras Kis, Nan Zhang, Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]) more...
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Materials science ,Exciton ,FOS: Physical sciences ,Bioengineering ,02 engineering and technology ,01 natural sciences ,Condensed Matter::Materials Science ,Transition metal dichalcogenides, van der Waals heterostructures, interlayer exciton, magnetophotoluminescence, valley polarization ,Soft Condensed Matter and Nanomaterials ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,General Materials Science ,010306 general physics ,ComputingMilieux_MISCELLANEOUS ,Condensed matter physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Scattering ,Mechanical Engineering ,Degenerate energy levels ,Exchange interaction ,Heterojunction ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Polarization (waves) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Magnetic field ,[PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con] ,Charge carrier ,0210 nano-technology - Abstract
Degenerate extrema in the energy dispersion of charge carriers in solids, also referred to as valleys, can be regarded as a binary quantum degree of freedom, which can potentially be used to implement valleytronic concepts in van der Waals heterostructures based on transition metal dichalcogenides. Using magneto-photoluminescence spectroscopy, we achieve a deeper insight into the valley polarization and depolarization mechanisms of interlayer excitons formed across a MoS$_2$/MoSe$_2$/MoS$_2$ heterostructure. We account for the non-trivial behavior of the valley polarization as a function of the magnetic field by considering the interplay between exchange interaction and phonon mediated intervalley scattering in a system consisting of Zeeman-split energy levels. Our results represent a crucial step towards the understanding of the properties of interlayer excitons, with strong implications for the implementation of atomically thin valleytronic devices., Comment: just accepted in Nano Letters, DOI: 10.1021/acs.nanolett.8b01484 more...
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- 2019
33. High-field anomalies of equilibrium and ultrafast magnetism in rare-earth–transition-metal ferrimagnets
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Arata Tsukamoto, A. K. Zvezdin, A. Pogrebna, Th. Rasing, Peter C. M. Christianen, K. H. Prabhakara, Alexey Kimel, J. Becker, Andrei Kirilyuk, and M. D. Davydova
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FELIX Condensed Matter Physics ,Physics ,Condensed Matter - Materials Science ,Condensed matter physics ,Magnetism ,Slowdown ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Paramagnetism ,Hysteresis ,Magnetization ,Soft Condensed Matter and Nanomaterials ,Ferrimagnetism ,Spectroscopy of Solids and Interfaces ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Ground state - Abstract
Magneto-optical spectroscopy in fields up to 30 Tesla reveals anomalies in the equilibrium and ultrafast magnetic properties of the ferrimagnetic rare-earth-transition metal alloy TbFeCo. In particular, in the vicinity of the magnetization compensation temperature, each of the magnetizations of the antiferromagnetically coupled Tb and FeCo sublattices show triple hysteresis loops. Contrary to state-of-the-art theory, which explains such loops by sample inhomogeneities, here we show that they are an intrinsic property of the rare-earth ferrimagnets. Assuming that the rare-earth ions are paramagnetic and have a non-zero orbital momentum in the ground state and, therefore, a large magnetic anisotropy, we are able to reproduce the experimentally observed behavior in equilibrium. The same theory is also able to describe the experimentally observed critical slowdown of the spin dynamics in the vicinity of the magnetization compensation temperature, emphasizing the role played by the orbital momentum in static and ultrafast magnetism of ferrimagnets. more...
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- 2019
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34. Terahertz modulation of the Cotton-Mouton effect
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Peter C. M. Christianen, S. Barsaume, E. A. Mashkovich, Alexey Kimel, A. V. Telegin, K. A. Grishunin, Th. Rasing, and Yu. P. Sukhorukov
- Subjects
History ,Materials science ,business.industry ,Terahertz radiation ,Physics::Optics ,Solid State Chemistry ,Computer Science Applications ,Education ,Soft Condensed Matter and Nanomaterials ,Modulation ,Spectroscopy of Solids and Interfaces ,Optoelectronics ,business ,Cotton–Mouton effect - Abstract
The ultrafast dynamics of the magneto-optical response triggered in the ferromagnetic semiconductor CdCr2Se4 by an intense nearly single cycle THz pulse is investigated. The dependence on the strength and the polarity of the external magnetic field, and the polarization of the THz pulse can be explained by a phenomenological expression that attributes the observed dynamics to the Cotton-Mouton effect at THz frequencies. more...
- Published
- 2019
35. Terahertz Optomagnetism: Nonlinear THz Excitation of GHz Spin Waves in Antiferromagnetic FeBO3
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K. A. Grishunin, A. K. Zvezdin, Alexey Kimel, Roman V. Pisarev, Rostislav Mikhaylovskiy, M.B. Strugatsky, Peter C. M. Christianen, Th. Rasing, and E. A. Mashkovich
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Physics ,Condensed matter physics ,Terahertz radiation ,General Physics and Astronomy ,Physics::Optics ,01 natural sciences ,Magnetic field ,Amplitude ,Soft Condensed Matter and Nanomaterials ,Spin wave ,Electric field ,Excited state ,Spectroscopy of Solids and Interfaces ,0103 physical sciences ,010306 general physics ,Excitation ,Spin-½ - Abstract
A nearly single cycle intense terahertz (THz) pulse with peak electric and magnetic fields of $0.5\text{ }\text{ }\mathrm{MV}/\mathrm{cm}$ and 0.16 T, respectively, excites both modes of spin resonances in the weak antiferromagnet ${\mathrm{FeBO}}_{3}$. The high frequency quasiantiferromagnetic mode is excited resonantly and its amplitude scales linearly with the strength of the THz magnetic field, whereas the low frequency quasiferromagnetic mode is excited via a nonlinear mechanism that scales quadratically with the strength of the THz electric field and can be regarded as a THz inverse Cotton-Mouton effect. THz optomagnetism is shown to be more energy efficient than similar effects reported previously for the near-infrared spectral range. more...
- Published
- 2019
36. Interlayer Excitons in Transition-Metal Dichalcogenide Heterobilayers
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Christian Schüller, Jens Kunstmann, Nicola Paradiso, Gotthard Seifert, Alexey Chernikov, Philipp Nagler, Tobias Korn, Gerd Plechinger, Andrey Chaves, Frederick Stein, Peter C. M. Christianen, Mariana V. Ballottin, Fabian Mooshammer, Christoph Strunk, David R. Reichman, Anatolie A. Mitioglu, Sebastian Meier, and Rupert Huber more...
- Subjects
Van der waals heterostructures ,Materials science ,Transition metal ,Soft Condensed Matter and Nanomaterials ,Excited state ,Exciton ,Monolayer ,Coulomb ,Correlated Electron Systems ,Condensed Matter Physics ,Molecular physics ,Electronic, Optical and Magnetic Materials - Abstract
In heterobilayers consisting of different transition-metal dichalcogenide (TMDC) monolayers, optically excited electron-hole pairs can be spatially separated into the adjacent layers due to a type-II band alignment. However, they remain Coulomb correlated and form interlayer excitons (ILEs), which recombine radiatively. While these ILEs are observed in several TMDC material combinations, their characters and properties depend on the specific system. Herein, some of these peculiarities are demonstrated by comparing studies performed on two different heterobilayer combinations: MoS2-WSe2 and MoSe2-WSe2. more...
- Published
- 2019
37. An unforeseen polymorph of coronene by the application of magnetic fields during crystal growth
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Andrew Collins, Christopher Bell, Claudio Fontanesi, Simon R. Hall, Peter C. M. Christianen, Simon Crampin, Alexandros N. Papanikolopoulos, Hans Engelkamp, Gabriele Kociok-Köhn, Enrico Da Como, Jason Potticary, and Lui R. Terry more...
- Subjects
Soft Condensed Matter & Nanomaterials (HFML) ,Materials science ,Science ,General Physics and Astronomy ,Nanotechnology ,Crystal growth ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,02 engineering and technology ,Coronene ,010402 general chemistry ,Crystal engineering ,01 natural sciences ,Article ,General Biochemistry, Genetics and Molecular Biology ,Crystal ,chemistry.chemical_compound ,Polyaromatic hydrocarbon ,Molecule ,Polymorphism ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Multidisciplinary ,Molecular Materials ,General Chemistry ,021001 nanoscience & nanotechnology ,Quantitative Biology::Genomics ,0104 chemical sciences ,Magnetic field ,Crystal-growth ,Polymorphism (materials science) ,chemistry ,Chemical physics ,Biochemistry, Genetics and Molecular Biology (all) ,Chemistry (all) ,Physics and Astronomy (all) ,0210 nano-technology - Abstract
The continued development of novel drugs, proteins, and advanced materials strongly rely on our ability to self-assemble molecules in solids with the most suitable structure (polymorph) in order to exhibit desired functionalities. The search for new polymorphs remains a scientific challenge, that is at the core of crystal engineering and there has been a lack of effective solutions to this problem. Here we show that by crystallizing the polyaromatic hydrocarbon coronene in the presence of a magnetic field, a polymorph is formed in a β-herringbone structure instead of the ubiquitous γ-herringbone structure, with a decrease of 35° in the herringbone nearest neighbour angle. The β-herringbone polymorph is stable, preserves its structure under ambient conditions and as a result of the altered molecular packing of the crystals, exhibits significant changes to the optical and mechanical properties of the crystal., Polymorphism, the presence of different crystal structures of the same molecular system, provides an opportunity to discover new phenomena and properties. Here, the authors crystallize coronene in the presence of a magnetic field, forming a different polymorph, which remains stable under ambient conditions. more...
- Published
- 2016
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38. Shape characterization of polymersome morphologies via light scattering techniques
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Peter C. M. Christianen, Loai K. E. A. Abdelmohsen, Jan C. M. van Hest, Daniela A. Wilson, Roger S. M. Rikken, and Bio-Organic Chemistry
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Morphology ,Polymersomes ,Soft Condensed Matter & Nanomaterials (HFML) ,Materials science ,Hydrodynamic radius ,Polymers and Plastics ,02 engineering and technology ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,010402 general chemistry ,01 natural sciences ,Bio-Organic Chemistry ,Light scattering ,Optics ,Microscopy ,Materials Chemistry ,business.industry ,Organic Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Characterization (materials science) ,Asymmetric flow field flow fractionation ,Chemical physics ,Polymersome ,Radius of gyration ,SPHERES ,0210 nano-technology ,business - Abstract
Polymersomes, vesicles self-assembled from amphiphilic block copolymers, are well known for their robustness and for their broad applicability. Generating polymersomes of different shape is a topic of recent attention, specifically in the field of biomedical applications. To obtain information about their exact shape, tomography based on cryo-electron microscopy is usually the most preferred technique. Unfortunately, this technique is rather time consuming and expensive. Here we demonstrate an alternative analytical approach for the characterization of differently shaped polymersomes such as spheres, prolates and discs via the combination of multi-angle light scattering (MALS) and quasi-elastic light scattering (QELS). The use of these coupled techniques allowed for accurate determination of both the radius of gyration (Rg) and the hydrodynamic radius (Rh). This afforded us to determine the shape ratio ρ (Rg/Rh) with which we were able to distinguish between polymersome spheres, discs and rods. more...
- Published
- 2016
- Full Text
- View/download PDF
39. Magnetic-Field-Induced Rotation of Polarized Light Emission from Monolayer WS2
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Ashish Arora, Gerd Plechinger, Christian Schüller, Steffen Michaelis de Vasconcellos, Peter C. M. Christianen, Philipp Nagler, Robert Schmidt, Tobias Korn, Rudolf Bratschitsch, Mariana V. Ballottin, and Andrés Granados del Águila more...
- Subjects
Physics ,Soft Condensed Matter & Nanomaterials (HFML) ,Zeeman effect ,business.industry ,Linear polarization ,General Physics and Astronomy ,02 engineering and technology ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,Magnetic field ,symbols.namesake ,Optics ,0103 physical sciences ,Monolayer ,symbols ,Atomic physics ,010306 general physics ,0210 nano-technology ,business ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Excitation - Abstract
We control the linear polarization of emission from the coherently emitting ${K}^{+}$ and ${K}^{\ensuremath{-}}$ valleys (valley coherence) in monolayer ${\mathrm{WS}}_{2}$ with an out-of-plane magnetic field of up to 25 T. The magnetic-field-induced valley Zeeman splitting causes a rotation of the emission polarization with respect to the excitation by up to 35\ifmmode^\circ\else\textdegree\fi{} and reduces the polarization degree by up to 16%. We explain both of these phenomena with a model based on two noninteracting coherent two-level systems. We deduce that the coherent light emission from the valleys decays with a time constant of ${\ensuremath{\tau}}_{c}=260\text{ }\text{ }\mathrm{fs}$. more...
- Published
- 2016
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40. Facilities for simulation of microgravity in the ESA ground-based facility programme
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Jack J. W. A. van Loon, Thu Jennifer Ngo Anh, Marcel Egli, Peter C. M. Christianen, Sonja Brungs, Ruth Hemmersbach, Simon L. Wuest, Maxillofacial Surgery (VUmc), MKA VUmc (ORM, ACTA), MOVE Research Institute, and Oral and Maxillofacial Surgery / Oral Pathology more...
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Soft Condensed Matter & Nanomaterials (HFML) ,Computer science ,business.industry ,Simulated microgravity ,Applied Mathematics ,General Engineering ,General Physics and Astronomy ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,01 natural sciences ,Space exploration ,010305 fluids & plasmas ,Modeling and Simulation ,Random Positioning Machine (RPM) ,0103 physical sciences ,Levitation ,Aerospace engineering ,010306 general physics ,business ,Clinostat ,Magnetic levitation - Abstract
Knowledge of the role of gravity in fundamental biological processes and, consequently, the impact of exposure to microgravity conditions provide insight into the basics of the development of life as well as enabling long-term space exploration missions. However, experimentation in real microgravity is expensive and scarcely available; thus, a variety of platforms have been developed to provide, on Earth, an experimental condition comparable to real microgravity. With the aim of simulating microgravity conditions, different ground-based facilities (GBF) have been constructed such as clinostats and random positioning machines as well as magnets for magnetic levitation. Here, we give an overview of ground-based facilities for the simulation of microgravity which were used in the frame of an ESA ground-based research programme dedicated to providing scientists access to these experimental capabilities in order to prepare their space experiments. more...
- Published
- 2016
- Full Text
- View/download PDF
41. Directed peptide amphiphile assembly using aqueous liquid crystal templates in magnetic fields
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Paul H. J. Kouwer, Peter C. M. Christianen, Masoumeh Keshavarz, and Pim van der Asdonk
- Subjects
Soft Condensed Matter & Nanomaterials (HFML) ,Materials science ,Protein Conformation ,Nanotechnology ,02 engineering and technology ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,010402 general chemistry ,01 natural sciences ,Liquid crystal ,Lyotropic ,Peptide amphiphile ,Soft matter ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Molecular Materials ,Water ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Liquid Crystals ,0104 chemical sciences ,Magnetic field ,Magnetic Fields ,Template ,Chromonic ,Anisotropy ,Diamagnetism ,Peptides ,0210 nano-technology - Abstract
An alignment technique based on the combination of magnetic fields and a liquid crystal (LC) template uses the advantages of both approaches: the magnetic fields offer non-contact methods that apply to all sample sizes and shapes, whilst the LC templates offer high susceptibilities. The combination introduces a route to control the spatial organization of materials with low intrinsic susceptibilities. We demonstrate that we can unidirectionally align one such material, peptide amphiphiles in water, on a centimeter scale at a tenfold lower magnetic field by using a lyotropic chromonic liquid crystal as a template. We can transform the aligned supramolecular assemblies into optically active π-conjugated polymers after photopolymerization. Lastly, by reducing the magnetic field strength needed for addressing these assemblies, we are able to create more complex structures by initiating self-assembly of our supramolecular materials under competing alignment forces between the magnetically induced alignment of the assemblies (with a positive diamagnetic anisotropy) and the elastic force dominated alignment of the template (with a negative diamagnetic anisotropy), which is directed orthogonally. Although the approach is still in its infancy and many critical parameters need optimization, we believe that it is a very promising technique to create tailor-made complex structures of (aqueous) functional soft matter. more...
- Published
- 2016
42. Spatial extent of the excited exciton states in WS$_2$ monolayers from diamagnetic shifts
- Author
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Takashi Taniguchi, Andreas V. Stier, Tobias Korn, Johannes Holler, Mariana V. Ballottin, Alexey Chernikov, Jonas Zipfel, Peter C. M. Christianen, Scott A. Crooker, Kenji Watanabe, Philipp Nagler, and Anatolie A. Mitioglu more...
- Subjects
Exciton ,FOS: Physical sciences ,Correlated Electron Systems ,02 engineering and technology ,01 natural sciences ,symbols.namesake ,Condensed Matter::Materials Science ,Effective mass (solid-state physics) ,Soft Condensed Matter and Nanomaterials ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,010306 general physics ,Physics ,Zeeman effect ,Condensed Matter - Mesoscale and Nanoscale Physics ,ddc:530 ,Radius ,530 Physik ,021001 nanoscience & nanotechnology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Excited state ,symbols ,Quasiparticle ,Diamagnetism ,Atomic physics ,0210 nano-technology ,Ground state - Abstract
We experimentally study the radii of excitons in hBN-encapsulated WS2 monolayers by means of magneto-optical reflectance spectroscopy at cryogenic temperatures in magnetic fields up to 29 T. We observe field-induced energy shifts of the exciton ground and excited states due to valley Zeeman and diamagnetic effects. We find the g factor of the first excited state of $-4.2(+/-0.1) to be essentially equal to that of the ground state of -4.35(+/-0.1). From diamagnetic shifts we determine the root mean square radii of the excitons. The radius of the first excited state is found to be 5-8 nm and that of the ground state around 2 nm. Our results further confirm the Wannier-Mott nature of the exciton quasiparticles in monolayer semiconductors and the assignment of the optical resonances in absorption-type measurements. They also provide additional support for the applicability of the effective mass hydrogenlike models in these systems., accepted for publication in Phys. Rev. B more...
- Published
- 2018
43. Intervalley Scattering of Interlayer Excitons in a MoS
- Author
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Alessandro, Surrente, Łukasz, Kłopotowski, Nan, Zhang, Michal, Baranowski, Anatolie A, Mitioglu, Mariana V, Ballottin, Peter C M, Christianen, Dumitru, Dumcenco, Yen-Cheng, Kung, Duncan K, Maude, Andras, Kis, and Paulina, Plochocka more...
- Abstract
Degenerate extrema in the energy dispersion of charge carriers in solids, also referred to as valleys, can be regarded as a binary quantum degree of freedom, which can potentially be used to implement valleytronic concepts in van der Waals heterostructures based on transition metal dichalcogenides. Using magneto-photoluminescence spectroscopy, we achieve a deeper insight into the valley polarization and depolarization mechanisms of interlayer excitons formed across a MoS more...
- Published
- 2018
44. Optical spectroscopy of interlayer excitons in TMDC heterostructures: exciton dynamics, interactions, and giant valley-selective magnetic splitting
- Author
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Rupert Huber, Philipp Nagler, Christian Schüller, Christoph Strunk, Alexey Chernikov, Tobias Korn, Gerd Plechinger, Sebastian Meier, Fabian Mooshammer, Mariana V. Ballotin, Peter C. M. Christianen, Anatolie A. Mitioglu, and Nicola Paradiso more...
- Subjects
Condensed Matter::Materials Science ,Dipole ,Materials science ,Photoluminescence ,Condensed matter physics ,Magnetic moment ,Excited state ,Exciton ,Heterojunction ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Excitation ,Magnetic field - Abstract
Two-dimensional transition-metal dichalcogenides (TMDCs) have recently emerged as a promising class of materials. A fascinating aspect of these atomically thin crystals is the possibility of combining different TMDCs into heterostructures. For several TMDC combinations, a staggered band alignment occurs, so that optically excited electron-hole pairs are spatially separated into different layers and form interlayer excitons (IEX). Here, we report on time-resolved, low-temperature photoluminescence (PL) of these IEX in a MoSe2-WSe2 heterostructure. In the time-resolved measurements, we observe indications of IEX diffusion in an inhomogeneous potential landscape. Excitation-density-dependent measurements reveal a dipolar, repulsive exciton-exciton interaction. PL measurements in applied magnetic fields show a giant valley-selective splitting of the IEX luminescence, with an effective g factor of about -15. This large value stems from the alignment of K+ and K- valleys of the constituent monolayers in our heterostructure, making intervalley transitions optically bright, so that contributions to the field-induced splitting arising from electron and hole valley magnetic moments add up. This giant splitting enables us to generate a near-unity valley polarization of interlayer excitons even under linearly polarized excitation by applying sufficiently large magnetic fields. more...
- Published
- 2018
- Full Text
- View/download PDF
45. Site-selective measurement of coupled spin pairs in an organic semiconductor
- Author
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Sam L. Bayliss, P. Plochocka, Karl J. Thorley, Neil C. Greenham, Richard H. Friend, Alexei D. Chepelianskii, John E. Anthony, K. M. Yunusova, Akshay Rao, Krzysztof Galkowski, Jan Behrends, Anatolie A. Mitioglu, Robert Bittl, Alessandro Surrente, Leah R. Weiss, Zhuo Yang, Peter C. M. Christianen, Surrente, A [0000-0003-4078-4965], Apollo - University of Cambridge Repository, Laboratoire national des champs magnétiques intenses - Toulouse (LNCMI-T), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), ANR-16-CE30-0013,SPINEX_1,Spintronique des exitons triplets dans la limite quantique(2016), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]) more...
- Subjects
Coupled spin pairs ,organic ,biological systems ,FOS: Physical sciences ,exchange coupling ,02 engineering and technology ,triplet excitons ,01 natural sciences ,Molecular physics ,Soft Condensed Matter and Nanomaterials ,Physics - Chemical Physics ,0103 physical sciences ,Singlet state ,010306 general physics ,Spin (physics) ,organic semiconductors ,ComputingMilieux_MISCELLANEOUS ,Physics ,Organic electronics ,Chemical Physics (physics.chem-ph) ,spintronics ,Condensed Matter - Materials Science ,Multidisciplinary ,Spintronics ,physics ,Intermolecular force ,singlet fission ,500 Naturwissenschaften und Mathematik::530 Physik::530 Physik ,Materials Science (cond-mat.mtrl-sci) ,021001 nanoscience & nanotechnology ,Organic semiconductor ,[PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con] ,organic spintronics ,Singlet fission ,Physical Sciences ,0210 nano-technology ,Luminescence - Abstract
From organic electronics to biological systems, understanding the role of intermolecular interactions between spin pairs is a key challenge. Here we show how such pairs can be selectively addressed with combined spin and optical sensitivity. We demonstrate this for bound pairs of spin-triplet excitations formed by singlet fission, with direct applicability across a wide range of synthetic and biological systems. We show that the site sensitivity of exchange coupling allows distinct triplet pairs to be resonantly addressed at different magnetic fields, tuning them between optically bright singlet ([Formula: see text]) and dark triplet quintet ([Formula: see text]) configurations: This induces narrow holes in a broad optical emission spectrum, uncovering exchange-specific luminescence. Using fields up to 60 T, we identify three distinct triplet-pair sites, with exchange couplings varying over an order of magnitude (0.3-5 meV), each with its own luminescence spectrum, coexisting in a single material. Our results reveal how site selectivity can be achieved for organic spin pairs in a broad range of systems., This work was supported by HFMLRU/ FOM and LNCMI-CNRS, members of the European Magnetic Field Laboratory (EMFL) and by EPSRC (UK) via its membership to the EMFL (grant no. EP/N01085X/1 and NS/A000060/1) and through grant no. EP/M005143/1. L.R.W. acknowledges support of the Gates-Cambridge and Winton Scholarships. We acknowledge support from Labex ANR-10-LABX-0039-PALM, ANR SPINEX, and DFG SPP-1601 (Bi-464/10-2). more...
- Published
- 2018
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46. Zeeman Splitting and Inverted Polarization of Biexciton Emission in Monolayer WS2
- Author
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Takashi Taniguchi, Christian Schüller, Mikhail M. Glazov, Philipp Nagler, Peter C. M. Christianen, Tobias Korn, Mikhail V. Durnev, Alexey Chernikov, Anatolie A. Mitioglu, Kenji Watanabe, and Mariana V. Ballottin more...
- Subjects
Soft Condensed Matter & Nanomaterials (HFML) ,Photoluminescence ,Exciton ,FOS: Physical sciences ,General Physics and Astronomy ,Correlated Electron Systems ,Position and momentum space ,Correlated Electron Systems / High Field Magnet Laboratory (HFML) ,02 engineering and technology ,01 natural sciences ,Molecular physics ,symbols.namesake ,Soft Condensed Matter and Nanomaterials ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,0103 physical sciences ,010306 general physics ,Biexciton ,Condensed Matter::Quantum Gases ,Physics ,Zeeman effect ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter::Other ,Linear polarization ,ddc:530 ,530 Physik ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,Polarization (waves) ,symbols ,0210 nano-technology ,Excitation - Abstract
Atomically thin semiconductors provide an ideal testbed to investigate the physics of Coulomb-bound many-body states. We shed light on the intricate structure of such complexes by studying the magnetic-field-induced splitting of biexcitons in monolayer ${\mathrm{WS}}_{2}$ using polarization-resolved photoluminescence spectroscopy in out-of-plane magnetic fields up to 30 T. The observed $g$ factor of the biexciton amounts to about $\ensuremath{-}3.9$, closely matching the $g$ factor of the neutral exciton. The biexciton emission shows an inverted circular field-induced polarization upon linearly polarized excitation; i.e., it exhibits preferential emission from the high-energy peak in a magnetic field. This phenomenon is explained by taking into account the hybrid configuration of the biexciton constituents in momentum space and their respective energetic behavior in magnetic fields. Our findings reveal the critical role of dark excitons in the composition of this many-body state. more...
- Published
- 2018
47. Unusual spin properties of InP wurtzite nanowires revealed by Zeeman splitting spectroscopy
- Author
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Qiang Gao, Peter C. M. Christianen, Antonio Polimeni, Jaroslav Fabian, Hark Hoe Tan, Benedikt Scharf, Davide Tedeschi, M. De Luca, P. E. Faria Junior, A. Granados del Águila, and Chennupati Jagadish
- Subjects
Sublinear function ,FOS: Physical sciences ,02 engineering and technology ,01 natural sciences ,symbols.namesake ,Condensed Matter::Materials Science ,amgnetic field ,Soft Condensed Matter and Nanomaterials ,0103 physical sciences ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,010306 general physics ,Anisotropy ,Wurtzite crystal structure ,Spin-½ ,Physics ,Zeeman effect ,Condensed Matter - Mesoscale and Nanoscale Physics ,Spintronics ,Condensed matter physics ,ddc:530 ,nanowires ,Landau quantization ,021001 nanoscience & nanotechnology ,Coupling (probability) ,530 Physik ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,symbols ,0210 nano-technology - Abstract
The knowledge of the value and anisotropy of the gyromagnetic factor in semiconducting nanowires (NWs) is crucial for their potential applications in several fields, such as spintronics and topological quantum computation. Here, we present a complete experimental and theoretical investigation of the Zeeman splitting of the fundamental exciton transition in an important material system: wurtzite (WZ) InP NWs. The excitonic $g$ factors are derived by the Zeeman splitting of the spin levels observed by photoluminescence measurements under magnetic fields $\stackrel{P\vec}{B}$ up to 29 T. In addition to being about three times greater than in zincblende InP, the $g$ factor in the WZ phase is strongly anisotropic (50%) upon variation of the direction of $\stackrel{P\vec}{B}$ from parallel to perpendicular to the NW axis. Moreover, it exhibits a marked sublinear dependence on $\stackrel{P\vec}{B}$ whenever $\stackrel{P\vec}{B}$ points along the NW axis, a feature common to other non-nitride III-V WZ NWs but never properly understood. All these features are well accounted for by a realistic $k\ifmmode\cdot\else\textperiodcentered\fi{}p$ modeling of the Landau levels in WZ InP with the envelope function approximation including excitonic effects. The nonlinearity is spin dependent and due to the coupling between the heavy-hole- and light-hole-like Landau levels. This is indeed a general signature of the bulk WZ structure not requiring quantum confinement nor NW geometry, and is demonstrated to hold also for GaAs, InAs and GaN WZ crystals as reported by Faria Junior et al. [Phys. Rev. B, present issue]. Our study solves the outstanding puzzle of the nonlinear Zeeman splitting found in several III-V WZ NWs. more...
- Published
- 2018
- Full Text
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48. Using magnetic birefringence to determine the molecular arrangement of supramolecular nanostructures
- Author
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Jeroen C Gielen, Igor O Shklyarevskiy, Albertus P H J Schenning, Peter C M Christianen and J C Maan
- Subjects
magnetic field ,birefringence ,sexithiophene ,conjugated oligomers ,supramolecular aggregates ,alignment ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Biotechnology ,TP248.13-248.65 - Abstract
Supramolecular aggregates can be aligned in solution using a magnetic field. Because of the optical anisotropy of the molecular building blocks, the alignment results in an anisotropic refractive index of the solution parallel and perpendicular to the magnetic field. We present a model for calculating the magnetic birefringence, using solely the magnetic susceptibilities and optical polarizabilities of the molecules, for any molecular arrangement. We demonstrate that magnetic birefringence is a very sensitive tool for determining the molecular organization within supramolecular aggregates. more...
- Published
- 2009
49. Negatively Charged and Dark Excitons in CsPbBr
- Author
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Damien, Canneson, Elena V, Shornikova, Dmitri R, Yakovlev, Tobias, Rogge, Anatolie A, Mitioglu, Mariana V, Ballottin, Peter C M, Christianen, Emmanuel, Lhuillier, Manfred, Bayer, and Louis, Biadala
- Abstract
The optical properties of colloidal cesium lead halide perovskite (CsPbBr
- Published
- 2017
50. Rotation of polarized light emission from monolayer WS2 induced by high magnetic fields
- Author
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Rudolf Bratschitsch, Ashish Arora, Andrés Granados del Águila, Tobias Korn, Peter C. M. Christianen, Robert Schmidt, Christian Schüller, Gerd Plechinger, Steffen Michaelis de Vasconcellos, Mariana V. Ballottin, and Philipp Nagler more...
- Subjects
Materials science ,Condensed matter physics ,business.industry ,Exciton ,Electronic structure ,01 natural sciences ,Magnetic field ,Semiconductor ,0103 physical sciences ,Valleytronics ,Monolayer ,Direct and indirect band gaps ,010306 general physics ,Spin (physics) ,business - Abstract
Monolayers of the transition metal dichalcogenides (TMDCs) MoS 2 , MoSe 2 , WS 2 , WSe 2 and MoTe 2 are a new class of atomically thin, direct band gap semiconductors with extraordinary optical and electronic properties. Due to their unique electronic structure the spin and valley (K+ or K−) of the excitons are locked, which allows for selective, optical addressing of the valleys. These properties render atomically thin TMDCs promising materials for applications in the field of “valleytronics”, where the valley index is used as a carrier for quantum information. more...
- Published
- 2017
- Full Text
- View/download PDF
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