819 results on '"Rotenberg, Eli"'
Search Results
2. Large Exciton Binding Energy in the Bulk van der Waals Magnet CrSBr
- Author
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Smolenski, Shane, Wen, Ming, Li, Qiuyang, Downey, Eoghan, Alfrey, Adam, Liu, Wenhao, Kondusamy, Aswin L. N., Bostwick, Aaron, Jozwiak, Chris, Rotenberg, Eli, Zhao, Liuyan, Deng, Hui, Lv, Bing, Zgid, Dominika, Gull, Emanuel, and Jo, Na Hyun
- Subjects
Condensed Matter - Materials Science - Abstract
Excitons, bound electron-hole pairs, influence the optical properties in strongly interacting solid state systems. Excitons and their associated many-body physics are typically most stable and pronounced in monolayer materials. Bulk systems with large exciton binding energies, on the other hand, are rare and the mechanisms driving their stability are still relatively unexplored. Here, we report an exceptionally large exciton binding energy in single crystals of the bulk van der Waals antiferromagnet CrSBr. Utilizing state-of-the-art angle-resolved photoemission spectroscopy and self-consistent ab-initio GW calculations, we present direct spectroscopic evidence that robust electronic and structural anisotropy can significantly amplify the exciton binding energy within bulk crystals. Furthermore, the application of a vertical electric field enables broad tunability of the optical and electronic properties. Our results indicate that CrSBr is a promising material for the study of the role of anisotropy in strongly interacting bulk systems and for the development of exciton-based optoelectronics.
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- 2024
3. Revealing the EuCd_{2}As_{2} Semiconducting Band Gap via n-type La-Doping
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Nelson, Ryan A., King, Jesaiah, Cheng, Shuyu, Williams, Archibald J., Jozwiak, Christopher, Bostwick, Aaron, Rotenberg, Eli, Sasmal, Souvik, Kao, I-Hsuan, Tiwari, Aalok, Jones, Natalie R., Cai, Chuting, Martin, Emma, Dolocan, Andrei, Shi, Li, Kawakami, Roland, Heremans, Joseph P., Katoch, Jyoti, and Goldberger, Joshua E.
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Condensed Matter - Materials Science - Abstract
EuCd_{2}As_{2} has attracted considerable interest as one of the few magnetic Weyl semimetal candidate materials, although recently there have been emerging reports that claim it to have a semiconducting electronic structure. To resolve this debate, we established the growth of n-type EuCd_{2}As_{2} crystals, to directly visualize the nature of the conduction band using angle resolve photoemission spectroscopy (ARPES). We show that La-doping leads to n-type transport signatures in both the thermopower and Hall effect measurements, in crystals with doping levels at 2 - 6 x 10^{17} e^{-} cm^{-3}. Both p-type and n-type doped samples exhibit antiferromagnetic ordering at 9 K. ARPES experiments at 6 K clearly show the presence of the conduction band minimum at 0.8 eV above the valence band maximum, which is further corroborated by the observation of a 0.71 - 0.72 eV band gap in room temperature diffuse reflectance absorbance measurements. Together these findings unambiguously show that EuCd_{2}As_{2} is indeed a semiconductor with a substantial band gap and not a topological semimetal.
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- 2024
4. Nodal fermions in a strongly spin-orbit coupled frustrated pyrochlore superconductor
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Oh, Dongjin, Kang, Junha, Qian, Yuting, Fang, Shiang, Kang, Mingu, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Checkelsky, Joseph G., Fu, Liang, Klimczuk, Tomasz, Winiarski, Michal J., Yang, Bohm-Jung, and Comin, Riccardo
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Condensed Matter - Materials Science - Abstract
The pyrochlore lattice, a three-dimensional network of corner-sharing tetrahedra, is a promising material playground for correlated topological phases arising from the interplay between spin-orbit coupling (SOC) and electron-electron interactions. Due to its geometrically frustrated lattice structure, exotic correlated states on the pyrochlore lattice have been extensively studied using various spin Hamiltonians in the localized limit. On the other hand, the topological properties of the electronic structure in the pyrochlore lattice have rarely been explored, due to the scarcity of pyrochlore materials in the itinerant paramagnetic limit. Here, we explore the topological electronic band structure of pyrochlore superconductor RbBi$_{2}$ using angle-resolved photoemission spectroscopy. Thanks to the strong SOC of the Bi pyrochlore network, we experimentally confirm the existence of three-dimensional (3D) massless Dirac fermions enforced by nonsymmorphic symmetry, as well as a 3D quadratic band crossing protected by cubic crystalline symmetry. Furthermore, we identify an additional 3D linear Dirac dispersion associated with band inversion protected by threefold rotation symmetry. These observations reveal the rich non-trivial band topology of itinerant pyrochlore lattice systems in the strong SOC regime. Through manipulation of electron correlations and SOC of the frustrated pyrochlore lattices, this material platform is a natural host for exotic phases of matter, including the fractionalized quantum spin Hall effect in the topological Mott insulator phase, as well as axion electrodynamics in the axion insulator phase., Comment: 18 pages, 4 figures
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- 2024
5. Achieving environmental stability in an atomically thin quantum spin Hall insulator via graphene intercalation.
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Kim, Timur, Cacho, Cephise, Lee, Tien-Lin, Sangiovanni, Giorgio, Moser, Simon, Claessen, Ralph, Schmitt, Cedric, Erhardt, Jonas, Eck, Philipp, Schmitt, Matthias, Lee, Kyungchan, Keßler, Philipp, Wagner, Tim, Spring, Merit, Liu, Bing, Enzner, Stefan, Kamp, Martin, Jovic, Vedran, Jozwiak, Chris, Rotenberg, Eli, and Bostwick, Aaron
- Abstract
Atomic monolayers on semiconductor surfaces represent an emerging class of functional quantum materials in the two-dimensional limit - ranging from superconductors and Mott insulators to ferroelectrics and quantum spin Hall insulators. Indenene, a triangular monolayer of indium with a gap of ~ 120 meV is a quantum spin Hall insulator whose micron-scale epitaxial growth on SiC(0001) makes it technologically relevant. However, its suitability for room-temperature spintronics is challenged by the instability of its topological character in air. It is imperative to develop a strategy to protect the topological nature of indenene during ex situ processing and device fabrication. Here we show that intercalation of indenene into epitaxial graphene provides effective protection from the oxidising environment, while preserving an intact topological character. Our approach opens a rich realm of ex situ experimental opportunities, priming monolayer quantum spin Hall insulators for realistic device fabrication and access to topologically protected edge channels.
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- 2024
6. Tuning commensurability in twisted van der Waals bilayers
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Li, Yanxing, Zhang, Fan, Ha, Viet-Anh, Lin, Yu-Chuan, Dong, Chengye, Gao, Qiang, Liu, Zhida, Liu, Xiaohui, Ryu, Sae Hee, Kim, Hyunsue, Jozwiak, Chris, Bostwick, Aaron, Watanabe, Kenji, Taniguchi, Takashi, Kousa, Bishoy, Li, Xiaoqin, Rotenberg, Eli, Khalaf, Eslam, Robinson, Joshua A, Giustino, Feliciano, and Shih, Chih-Kang
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Physical Sciences ,Condensed Matter Physics ,General Science & Technology - Abstract
Moiré superlattices based on van der Waals bilayers1-4 created at small twist angles lead to a long wavelength pattern with approximate translational symmetry. At large twist angles (θt), moiré patterns are, in general, incommensurate except for a few discrete angles. Here we show that large-angle twisted bilayers offer distinctly different platforms. More specifically, by using twisted tungsten diselenide bilayers, we create the incommensurate dodecagon quasicrystals at θt = 30° and the commensurate moiré crystals at θt = 21.8° and 38.2°. Valley-resolved scanning tunnelling spectroscopy shows disparate behaviours between moiré crystals (with translational symmetry) and quasicrystals (with broken translational symmetry). In particular, the K valley shows rich electronic structures exemplified by the formation of mini-gaps near the valence band maximum. These discoveries demonstrate that bilayers with large twist angles offer a design platform to explore moiré physics beyond those formed with small twist angles.
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- 2024
7. Nature of charge density wave in kagome metal ScV6Sn6
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Lee, Seongyong, Won, Choongjae, Kim, Jimin, Yoo, Jonggyu, Park, Sudong, Denlinger, Jonathan, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Comin, Riccardo, Kang, Mingu, and Park, Jae-Hoon
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Quantum Physics ,Physical Sciences ,Engineering ,Physical sciences - Abstract
Recently, kagome lattice materials have emerged as a new model material platform for discovering and engineering novel quantum phases of matter. In this work, we elucidate the driving mechanism of the 3 × 3 charge order in a newly discovered kagome metal ScV6Sn6. Through multimodal investigations combining angle-resolved photoemission spectroscopy, phonon dispersion calculations, and phase diagram study, we identify the central role of unstable planar Sn and Sc phonon modes, while the electronic instability and van Hove singularities originating from the V kagome lattice have a marginal influence. Our results highlight that the 3 × 3 charge order in ScV6Sn6 is fundamentally distinguished from the electronically driven 2 × 2 charge order in the canonical kagome system AV3Sb5, uncovering a new mechanism to induce symmetry-breaking phase transition in kagome lattice materials.
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- 2024
8. Hopping frustration-induced flat band and strange metallicity in a kagome metal
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Ye, Linda, Fang, Shiang, Kang, Mingu, Kaufmann, Josef, Lee, Yonghun, John, Caolan, Neves, Paul M, Zhao, SY Frank, Denlinger, Jonathan, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Kaxiras, Efthimios, Bell, David C, Janson, Oleg, Comin, Riccardo, and Checkelsky, Joseph G
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Physical Sciences ,Condensed Matter Physics ,Mathematical Sciences ,Fluids & Plasmas ,Mathematical sciences ,Physical sciences - Abstract
The introduction of localized electronic states into a metal can alter its physical properties, for example enabling exotic metal physics including heavy fermion and strange metal behaviour. A common source of localized states in such systems are partially filled 4f and 5f shells because of the inherently compact nature of those orbitals. The interaction of electrons in these orbitals with the conduction sea is well described by the Kondo framework. However, there have also been observations of Kondo-like behaviour in 3d transition metal oxides and in 4d- and 5d-containing van der Waals heterostructures. This calls for a broader consideration of the physical requirements for Kondo systems. Here we show transport and thermodynamic hallmarks of heavy fermion and strange metal behaviour that arise in the kagome metal Ni3In, wherein the source of localized states is destructive interference-induced band flattening of partially filled Ni 3d states. With magnetic field and pressure tuning, we also find evidence that the system is proximate to quantum criticality, extending the analogy to f-electron Kondo lattices. These observations highlight the role of hopping frustration in metallic systems as a potential source for strong correlations. Additionally, this suggests a lattice-driven approach to realizing correlated metals with non-trivial band topology.
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- 2024
9. Controlling spin-orbit coupling to tailor type-II Dirac bands
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Lam, Nguyen Huu, Nguyen, Phuong Lien, Choi, Byoung Ki, Ly, Trinh Thi, Duvjir, Ganbat, Rhee, Tae Gyu, Jo, Yong Jin, Kim, Tae Heon, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Hwang, Younghun, Chang, Young Jun, Lee, Jaekwang, and Kim, Jungdae
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Strongly Correlated Electrons - Abstract
NiTe2, a type-II Dirac semimetal with strongly tilted Dirac band, has been explored extensively to understand its intriguing topological properties. Here, using density-functional theory (DFT) calculations, we report that the strength of spin-orbit coupling (SOC) in NiTe2 can be tuned by Se substitution. This results in negative shifts of the bulk Dirac point (BDP) while preserving the type-II Dirac band. Indeed, combined studies using scanning tunneling spectroscopy (STS) and angle-resolved photoemission spectroscopy (ARPES) confirm that the BDP in the NiTe2-xSex alloy moves from +0.1 eV (NiTe2) to -0.3 eV (NiTeSe) depending on the Se concentrations, indicating the effective tunability of type-II Dirac fermions. Our results demonstrate an approach to tailor the type-II Dirac band in NiTe2 by controlling the SOC strength via chalcogen substitution. This approach can be applicable to different types of topological materials., Comment: 25 pages, 4 figures
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- 2023
- Full Text
- View/download PDF
10. Orbital-selective metal skin induced by alkali-metal-dosing Mott-insulating Ca$_2$RuO$_4$
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Horio, M., Forte, F., Sutter, D., Kim, M., Fatuzzo, C. G., Matt, C. E., Moser, S., Wada, T., Granata, V., Fittipaldi, R., Sassa, Y., Gatti, G., Rønnow, H. M., Hoesch, M., Kim, T. K., Jozwiak, C., Bostwick, A., Rotenberg, Eli, Matsuda, I., Georges, A., Sangiovanni, G., Vecchione, A., Cuoco, M., and Chang, J.
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Condensed Matter - Strongly Correlated Electrons - Abstract
Doped Mott insulators are the starting point for interesting physics such as high temperature superconductivity and quantum spin liquids. For multi-band Mott insulators, orbital selective ground states have been envisioned. However, orbital selective metals and Mott insulators have been difficult to realize experimentally. Here we demonstrate by photoemission spectroscopy how Ca$_2$RuO$_4$, upon alkali-metal surface doping, develops a single-band metal skin. Our dynamical mean field theory calculations reveal that homogeneous electron doping of Ca$_2$RuO$_4$ results in a multi-band metal. All together, our results provide compelling evidence for an orbital-selective Mott insulator breakdown, which is unachievable via simple electron doping. Supported by a cluster model and cluster perturbation theory calculations, we demonstrate a novel type of skin metal-insulator transition induced by surface dopants that orbital-selectively hybridize with the bulk Mott state and in turn produce coherent in-gap states., Comment: A revised version of this manuscript will appear in Communications Physics
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- 2023
- Full Text
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11. A substitutional quantum defect in WS$_2$ discovered by high-throughput computational screening and fabricated by site-selective STM manipulation
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Thomas, John C., Chen, Wei, Xiong, Yihuang, Barker, Bradford A., Zhou, Junze, Chen, Weiru, Rossi, Antonio, Kelly, Nolan, Yu, Zhuohang, Zhou, Da, Kumari, Shalini, Barnard, Edward S., Robinson, Joshua A., Terrones, Mauricio, Schwartzberg, Adam, Ogletree, D. Frank, Rotenberg, Eli, Noack, Marcus M., Griffin, Sinéad, Raja, Archana, Strubbe, David A., Rignanese, Gian-Marco, Weber-Bargioni, Alexander, and Hautier, Geoffroy
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Condensed Matter - Materials Science ,Quantum Physics - Abstract
Point defects in two-dimensional materials are of key interest for quantum information science. However, the space of possible defects is immense, making the identification of high-performance quantum defects extremely challenging. Here, we perform high-throughput (HT) first-principles computational screening to search for promising quantum defects within WS$_2$, which present localized levels in the band gap that can lead to bright optical transitions in the visible or telecom regime. Our computed database spans more than 700 charged defects formed through substitution on the tungsten or sulfur site. We found that sulfur substitutions enable the most promising quantum defects. We computationally identify the neutral cobalt substitution to sulfur (Co$_{\rm S}^{0}$) as very promising and fabricate it with scanning tunneling microscopy (STM). The Co$_{\rm S}^{0}$ electronic structure measured by STM agrees with first principles and showcases an attractive new quantum defect. Our work shows how HT computational screening and novel defect synthesis routes can be combined to design new quantum defects., Comment: 38 pages, 19 figures
- Published
- 2023
12. Anomalous excitonic phase diagram in band-gap-tuned Ta2Ni(Se,S)5
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Chen, Cheng, Tang, Weichen, Chen, Xiang, Kang, Zhibo, Ding, Shuhan, Scott, Kirsty, Wang, Siqi, Li, Zhenglu, Ruff, Jacob P. C., Hashimoto, Makoto, Lu, Dong-Hui, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Neto, Eduardo H. da Silva, Birgeneau, Robert J., Chen, Yulin, Louie, Steven G., Wang, Yao, and He, Yu
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
During a band-gap-tuned semimetal-to-semiconductor transition, Coulomb attraction between electrons and holes can cause spontaneously formed excitons near the zero-band-gap point, or the Lifshitz transition point. This has become an important route to realize bulk excitonic insulators -- an insulating ground state distinct from single-particle band insulators. How this route manifests from weak to strong coupling is not clear. In this work, using angle-resolved photoemission spectroscopy (ARPES) and high-resolution synchrotron x-ray diffraction (XRD), we investigate the broken symmetry state across the semimetal-to-semiconductor transition in a leading bulk excitonic insulator candidate system Ta2Ni(Se,S)5. A broken symmetry phase is found to be continuously suppressed from the semimetal side to the semiconductor side, contradicting the anticipated maximal excitonic instability around the Lifshitz transition. Bolstered by first-principles and model calculations, we find strong interband electron-phonon coupling to play a crucial role in the enhanced symmetry breaking on the semimetal side of the phase diagram. Our results not only provide insight into the longstanding debate of the nature of intertwined orders in Ta2NiSe5, but also establish a basis for exploring band-gap-tuned structural and electronic instabilities in strongly coupled systems., Comment: 27 pages, 4 + 9 figures
- Published
- 2023
13. Discovery of interlayer plasmon polaron in graphene/WS$_2$ heterostructures
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Ulstrup, Søren, Veld, Yann in 't, Miwa, Jill A., Jones, Alfred J. H., McCreary, Kathleen M., Robinson, Jeremy T., Jonker, Berend T., Singh, Simranjeet, Koch, Roland J., Rotenberg, Eli, Bostwick, Aaron, Jozwiak, Chris, Rösner, Malte, and Katoch, Jyoti
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Harnessing electronic excitations involving coherent coupling to bosonic modes is essential for the design and control of emergent phenomena in quantum materials [1]. In situations where charge carriers induce a lattice distortion due to the electron-phonon interaction, the conducting states get "dressed". This leads to the formation of polaronic quasiparticles that dramatically impact charge transport, surface reactivity, thermoelectric and optical properties, as observed in a variety of crystals and interfaces composed of polar materials [2-6]. Similarly, when oscillations of the charge density couple to conduction electrons the more elusive plasmon polaron emerges [7], which has been detected in electron-doped semiconductors [8-10]. However, the exploration of polaronic effects on low energy excitations is still in its infancy in two-dimensional (2D) materials. Here, we present the discovery of an interlayer plasmon polaron in heterostructures composed of graphene on top of SL WS$_2$. By using micro-focused angle-resolved photoemission spectroscopy (microARPES) during in situ doping of the top graphene layer, we observe a strong quasiparticle peak accompanied by several carrier density-dependent shake-off replicas around the SL WS$_2$ conduction band minimum (CBM). Our results are explained by an effective many-body model in terms of a coupling between SL WS$_2$ conduction electrons and graphene plasmon modes. It is important to take into account the presence of such interlayer collective modes, as they have profound consequences for the electronic and optical properties of heterostructures that are routinely explored in many device architectures involving 2D transition metal dichalcogenides (TMDs) [11-15]., Comment: 25 pages, 9 figures including Supporting Information
- Published
- 2023
14. Nature of the current-induced insulator-to-metal transition in Ca$_2$RuO$_4$ as revealed by transport-ARPES
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Suen, Cissy T, Marković, Igor, Zonno, Marta, Zhdanovich, Sergey, Jo, Na-Hyun, Schmid, Michael, Hansmann, Philipp, Puphal, Pascal, Fürsich, Katrin, Zimmerman, Valentin, Smit, Steef, Au-Yeung, Christine, Zwartsenberg, Berend, Krautloher, Maximilian, Elfimov, Ilya S, Koch, Roland, Gorovikov, Sergey, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Keimer, Bernhard, and Damascelli, Andrea
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
The Mott insulator Ca$_2$RuO$_4$ exhibits a rare insulator-to-metal transition (IMT) induced by DC current. While structural changes associated with this transition have been tracked by neutron diffraction, Raman scattering, and x-ray spectroscopy, work on elucidating the response of the electronic degrees of freedom is still in progress. Here we unveil the current-induced modifications of the electronic states of Ca$_2$RuO$_4$ by employing angle-resolved photoemission spectroscopy (ARPES) in conjunction with four-probe transport. Two main effects emerge: a clear reduction of the Mott gap and a modification in the dispersion of the Ru-bands. The changes in dispersion occur exclusively along the $XM$ high-symmetry direction, parallel to the $b$-axis where the greatest in-plane lattice change occurs. These experimental observations are reflected in dynamical mean-field theory (DMFT) calculations simulated exclusively from the current-induced lattice constants, indicating a current driven structural transition as the primary mechanism of the IMT. Furthermore, we demonstrate this phase is distinct from the high-temperature zero-current metallic phase. Our results provide insight into the elusive nature of the current-induced IMT of Ca$_2$RuO$_4$ and advance the challenging, yet powerful, technique of transport-ARPES., Comment: 8 pages, 4 figures
- Published
- 2023
15. Epitaxial Kagome Thin Films as a Platform for Topological Flat Bands
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Cheng, Shuyu, Nrisimhamurty, M., Zhou, Tong, Bagues, Nuria, Zhou, Wenyi, Bishop, Alexander J., Lyalin, Igor, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, McComb, David W., Zutic, Igor, and Kawakami, Roland K.
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
Systems with flat bands are ideal for studying strongly correlated electronic states and related phenomena. Among them, kagome-structured metals such as CoSn have been recognized as promising candidates due to the proximity between the flat bands and the Fermi level. A key next step will be to realize epitaxial kagome thin films with flat bands to enable tuning of the flat bands across the Fermi level via electrostatic gating or strain. Here we report the band structures of epitaxial CoSn thin films grown directly on insulating substrates. Flat bands are observed using synchrotron-based angle-resolved photoemission spectroscopy (ARPES). The band structure is consistent with density functional theory (DFT) calculations, and the transport properties are quantitatively explained by the band structure and semiclassical transport theory. Our work paves the way to realize flat band-induced phenomena through fine-tuning of flat bands in kagome materials., Comment: 30 pages, 12 figures
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- 2023
- Full Text
- View/download PDF
16. Spectral Evidence for Local-Moment Ferromagnetism in van der Waals Metals Fe$_3$GaTe$_2$ and Fe$_3$GeTe$_2$
- Author
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Wu, Han, Hu, Chaowei, Xie, Yaofeng, Jang, Bo Gyu, Huang, Jianwei, Guo, Yucheng, Wu, Shan, Hu, Cheng, Yue, Ziqin, Shi, Yue, Ren, Zheng, Yilmaz, T., Vescovo, Elio, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Fedorov, Alexei, Denlinger, Jonathan, Klewe, Christoph, Shafer, Padraic, Lu, Donghui, Hashimoto, Makoto, Kono, Junichiro, Birgeneau, Robert J., Xu, Xiaodong, Zhu, Jian-Xin, Dai, Pengcheng, Chu, Jiun-Haw, and Yi, Ming
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Magnetism in two-dimensional (2D) materials has attracted considerable attention recently for both fundamental understanding of magnetism and their tunability towards device applications. The isostructural Fe$_3$GeTe$_2$ and Fe$_3$GaTe$_2$ are two members of the Fe-based van der Waals (vdW) ferromagnet family, but exhibit very different Curie temperatures (T$_C$) of 210 K and 360 K, respectively. Here, by using angle-resolved photoemission spectroscopy and density functional theory, we systematically compare the electronic structures of the two compounds. Qualitative similarities in the Fermi surface can be found between the two compounds, with expanded hole pockets in Fe$_3$GaTe$_2$ suggesting additional hole carriers compared to Fe$_3$GeTe$_2$. Interestingly, we observe no band shift in Fe$_3$GaTe$_2$ across its T$_C$ of 360 K, compared to a small shift in Fe$_3$GeTe$_2$ across its T$_C$ of 210 K. The weak temperature-dependent evolution strongly deviates from the expectations of an itinerant Stoner mechanism. Our results suggest that itinerant electrons have minimal contributions to the enhancement of T$_C$ in Fe$_3$GaTe$_2$ compared to Fe$_3$GeTe$_2$, and that the nature of ferromagnetism in these Fe-based vdW ferromagnets must be understood with considerations of the electron correlations.
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- 2023
- Full Text
- View/download PDF
17. Electronic Band Structure Changes across the Antiferromagnetic Phase Transition of Exfoliated MnPS3 Flakes Probed by μ‑ARPES
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Strasdas, Jeff, Pestka, Benjamin, Rybak, Miłosz, Budniak, Adam K, Leuth, Niklas, Boban, Honey, Feyer, Vitaliy, Cojocariu, Iulia, Baranowski, Daniel, Avila, José, Dudin, Pavel, Bostwick, Aaron, Jozwiak, Chris, Rotenberg, Eli, Autieri, Carmine, Amouyal, Yaron, Plucinski, Lukasz, Lifshitz, Efrat, Birowska, Magdalena, and Morgenstern, Markus
- Subjects
Quantum Physics ,Chemical Sciences ,Physical Sciences ,Condensed Matter Physics ,magnetic 2D materials ,angular resolved photoelectronspectroscopy ,layered magnetism ,mu-ARPES ,density functional theory ,angular resolved photoelectron spectroscopy ,μ-ARPES ,Nanoscience & Nanotechnology - Abstract
Exfoliated magnetic 2D materials enable versatile tuning of magnetization, e.g., by gating or providing proximity-induced exchange interaction. However, their electronic band structure after exfoliation has not been probed, presumably due to their photochemical sensitivity. Here, we provide micrometer-scale angle-resolved photoelectron spectroscopy of the exfoliated intralayer antiferromagnet MnPS3 above and below the Néel temperature down to one monolayer. Favorable comparison with density functional theory calculations enables identifying the orbital character of the observed bands. Consistently, we find pronounced changes across the Néel temperature for bands consisting of Mn 3d and 3p levels of adjacent S atoms. The deduced orbital mixture indicates that the superexchange is relevant for the magnetic interaction. There are only minor changes between monolayer and thicker films, demonstrating the predominant 2D character of MnPS3. The novel access is transferable to other MPX3 materials (M: transition metal, P: phosphorus, X: chalcogenide), providing several antiferromagnetic arrangements.
- Published
- 2023
18. Anomalous excitonic phase diagram in band-gap-tuned Ta2Ni(Se,S)5.
- Author
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Wang, Yao, He, Yu, Chen, Cheng, Tang, Weichen, Chen, Xiang, Kang, Zhibo, Ding, Shuhan, Scott, Kirsty, Wang, Siqi, Ruff, Jacob, Hashimoto, Makoto, Lu, Dong-Hui, Jozwiak, Chris, da Silva Neto, Eduardo, Chen, Yulin, Louie, Steven, Birgeneau, Robert, Rotenberg, Eli, Bostwick, Aaron, and Li, Zhenglu
- Abstract
During a band-gap-tuned semimetal-to-semiconductor transition, Coulomb attraction between electrons and holes can cause spontaneously formed excitons near the zero-band-gap point, or the Lifshitz transition point. This has become an important route to realize bulk excitonic insulators - an insulating ground state distinct from single-particle band insulators. How this route manifests from weak to strong coupling is not clear. In this work, using angle-resolved photoemission spectroscopy (ARPES) and high-resolution synchrotron x-ray diffraction (XRD), we investigate the broken symmetry state across the semimetal-to-semiconductor transition in a leading bulk excitonic insulator candidate system Ta2Ni(Se,S)5. A broken symmetry phase is found to be continuously suppressed from the semimetal side to the semiconductor side, contradicting the anticipated maximal excitonic instability around the Lifshitz transition. Bolstered by first-principles and model calculations, we find strong interband electron-phonon coupling to play a crucial role in the enhanced symmetry breaking on the semimetal side of the phase diagram. Our results not only provide insight into the longstanding debate of the nature of intertwined orders in Ta2NiSe5, but also establish a basis for exploring band-gap-tuned structural and electronic instabilities in strongly coupled systems.
- Published
- 2023
19. A substitutional quantum defect in WS2 discovered by high-throughput computational screening and fabricated by site-selective STM manipulation
- Author
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Thomas, John, Chen, Wei, Xiong, Yihuang, Barker, Bradford, Zhou, Junze, Chen, Weiru, Rossi, Antonio, Kelly, Nolan, Yu, Zhuohang, Zhou, Da, Kumari, Shalini, Barnard, Edward, Robinson, Joshua, Terrones, Mauricio, Schwartzberg, Adam, Ogletree, D Frank, Rotenberg, Eli, Noack, Marcus, Griffin, Sinéad, Raja, Archana, Strubbe, David, Rignanese, Gian-Marco, Weber-Bargioni, Alexander, and Hautier, Geoffroy
- Subjects
Quantum Physics ,Physical Sciences ,Condensed Matter Physics ,Bioengineering - Abstract
Abstract: Point defects in two-dimensional materials are of key interest for quantum information science. However, the space of possible defects is immense, making the identification of high-performance quantum defects extremely challenging. Here, we perform high-throughput (HT) first-principles computational screening to search for promising quantum defects within WS2, which present localized levels in the band gap that can lead to bright optical transitions in the visible or telecom regime. Our computed database spans more than 700 charged defects formed through substitution on the tungsten or sulfur site. We found that sulfur substitutions enable the most promising quantum defects. We computationally identify the neutral cobalt substitution to sulfur (Co$_{\rm S}^{0}$) as very promising and fabricate it with scanning tunneling microscopy (STM). The Co$_{\rm S}^{0}$ electronic structure measured by STM agrees with first principles and showcases an attractive new quantum defect. Our work shows how HT computational screening and novel defect synthesis routes can be combined to design new quantum defects.
- Published
- 2023
20. Weyl nodal ring states and Landau quantization with very large magnetoresistance in square-net magnet EuGa4.
- Author
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Lei, Shiming, Allen, Kevin, Huang, Jianwei, Moya, Jaime, Wu, Tsz, Casas, Brian, Zhang, Yichen, Oh, Ji, Hashimoto, Makoto, Lu, Donghui, Denlinger, Jonathan, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Balicas, Luis, Birgeneau, Robert, Foster, Matthew, Yi, Ming, Sun, Yan, and Morosan, Emilia
- Abstract
Magnetic topological semimetals allow for an effective control of the topological electronic states by tuning the spin configuration. Among them, Weyl nodal line semimetals are thought to have the greatest tunability, yet they are the least studied experimentally due to the scarcity of material candidates. Here, using a combination of angle-resolved photoemission spectroscopy and quantum oscillation measurements, together with density functional theory calculations, we identify the square-net compound EuGa4 as a magnetic Weyl nodal ring semimetal, in which the line nodes form closed rings near the Fermi level. The Weyl nodal ring states show distinct Landau quantization with clear spin splitting upon application of a magnetic field. At 2 K in a field of 14 T, the transverse magnetoresistance of EuGa4 exceeds 200,000%, which is more than two orders of magnitude larger than that of other known magnetic topological semimetals. Our theoretical model suggests that the non-saturating magnetoresistance up to 40 T arises as a consequence of the nodal ring state.
- Published
- 2023
21. Direct Visualization of the Charge Transfer in a Graphene/α-RuCl3 Heterostructure via Angle-Resolved Photoemission Spectroscopy.
- Author
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Rossi, Antonio, Johnson, Cameron, Balgley, Jesse, Watanabe, Kenji, Taniguchi, Takashi, Cothrine, Matthew, Mandrus, David, Jozwiak, Chris, Bostwick, Aaron, Henriksen, Erik, Francaviglia, Luca, Dettori, Riccardo, Rotenberg, Eli, Schmid, Andreas, Weber-Bargioni, Alexander, and Thomas, John
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Graphene ,a-RuCl3 ,angle-resolved photoemission spectroscopy ,electronic structure ,low energy electron microscopy ,p−n junction - Abstract
We investigate the electronic properties of a graphene and α-ruthenium trichloride (α-RuCl3) heterostructure using a combination of experimental techniques. α-RuCl3 is a Mott insulator and a Kitaev material. Its combination with graphene has gained increasing attention due to its potential applicability in novel optoelectronic devices. By using a combination of spatially resolved photoemission spectroscopy and low-energy electron microscopy, we are able to provide a direct visualization of the massive charge transfer from graphene to α-RuCl3, which can modify the electronic properties of both materials, leading to novel electronic phenomena at their interface. A measurement of the spatially resolved work function allows for a direct estimate of the interface dipole between graphene and α-RuCl3. Their strong coupling could lead to new ways of manipulating electronic properties of a two-dimensional heterojunction. Understanding the electronic properties of this structure is pivotal for designing next generation low-power optoelectronics devices.
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- 2023
22. Comparative Electronic Structures of the Chiral Helimagnets Cr1/3NbS2 and Cr1/3TaS2
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Xie, Lilia S, Gonzalez, Oscar, Li, Kejun, Michiardi, Matteo, Gorovikov, Sergey, Ryu, Sae Hee, Fender, Shannon S, Zonno, Marta, Jo, Na Hyun, Zhdanovich, Sergey, Jozwiak, Chris, Bostwick, Aaron, Husremović, Samra, Erodici, Matthew P, Mollazadeh, Cameron, Damascelli, Andrea, Rotenberg, Eli, Ping, Yuan, and Bediako, D Kwabena
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Engineering ,Chemical Sciences ,Materials ,Chemical sciences - Abstract
Magnetic materials with noncollinear spin textures are promising for spintronic applications. To realize practical devices, control over the length and energy scales of such spin textures is imperative. The chiral helimagnets Cr1/3NbS2 and Cr1/3TaS2 exhibit analogous magnetic-phase diagrams with different real-space periodicities and field dependence, positioning them as model systems for studying the relative strengths of the microscopic mechanisms giving rise to exotic spin textures. Although the electronic structure of the Nb analogue has been experimentally investigated, the Ta analogue has received far less attention. Here, we present a comprehensive suite of electronic structure studies on both Cr1/3NbS2 and Cr1/3TaS2 using angle-resolved photoemission spectroscopy and density functional theory. We show that bands in Cr1/3TaS2 are more dispersive than their counterparts in Cr1/3NbS2, resulting in markedly different Fermi wavevectors. The fact that their qualitative magnetic phase diagrams are nevertheless identical shows that hybridization between the intercalant and host lattice mediates the magnetic exchange interactions in both of these materials. We ultimately find that ferromagnetic coupling is stronger in Cr1/3TaS2, but larger spin-orbit coupling (and a stronger Dzyaloshinskii-Moriya interaction) from the heavier host lattice ultimately gives rise to shorter spin textures.
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- 2023
23. Direct visualization of the charge transfer in Graphene/$\alpha$-RuCl$_3$ heterostructure
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Rossi, Antonio, Dettori, Riccardo, Johnson, Cameron, Balgley, Jesse, Thomas, John C., Francaviglia, Luca, Schmid, Andreas K., Watanabe, Kenji, Taniguchi, Takashi, Cothrine, Matthew, Mandrus, David G., Jozwiak, Chris, Bostwick, Aaron, Henriksen, Erik A., Weber-Bargioni, Alexander, and Rotenberg, Eli
- Subjects
Condensed Matter - Materials Science - Abstract
We investigate the electronic properties of a graphene and $\alpha$-ruthenium trichloride (hereafter RuCl$_3$) heterostructure, using a combination of experimental and theoretical techniques. RuCl$_3$ is a Mott insulator and a Kitaev material, and its combination with graphene has gained increasing attention due to its potential applicability in novel electronic and optoelectronic devices. By using a combination of spatially resolved photoemission spectroscopy, low energy electron microscopy, and density functional theory (DFT) calculations we are able to provide a first direct visualization of the massive charge transfer from graphene to RuCl$_3$, which can modify the electronic properties of both materials, leading to novel electronic phenomena at their interface. The electronic band structure is compared to DFT calculations that confirm the occurrence of a Mott transition for RuCl$_3$. Finally, a measurement of spatially resolved work function allows for a direct estimate of the interface dipole between graphene and RuCl$_3$. The strong coupling between graphene and RuCl$_3$ could lead to new ways of manipulating electronic properties of two-dimensional lateral heterojunction. Understanding the electronic properties of this structure is pivotal for designing next generation low-power opto-electronics devices.
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- 2023
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24. Comparative Electronic Structures of the Chiral Helimagnets Cr1/3NbS2 and Cr1/3TaS2
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Xie, Lilia S., Gonzalez, Oscar, Li, Kejun, Michiardi, Matteo, Gorovikov, Sergey, Ryu, Sae Hee, Fender, Shannon S., Zonno, Marta, Jo, Na Hyun, Zhdanovich, Sergey, Jozwiak, Chris, Bostwick, Aaron, Husremovic, Samra, Erodici, Matthew P., Mollazadeh, Cameron, Damascelli, Andrea, Rotenberg, Eli, Ping, Yuan, and Bediako, D. Kwabena
- Subjects
Condensed Matter - Materials Science - Abstract
Magnetic materials with noncollinear spin textures are promising for spintronic applications. To realize practical devices, control over the length and energy scales of such spin textures is imperative. The chiral helimagnets Cr1/3NbS2 and Cr1/3TaS2 exhibit analogous magnetic phase diagrams with different real-space periodicities and field dependence, positioning them as model systems for studying the relative strengths of the microscopic mechanisms giving rise to exotic spin textures. Here, we carry out a comparative study of the electronic structures of Cr1/3NbS2 and Cr1/3TaS2 using angle-resolved photoemission spectroscopy and density functional theory. We show that bands in Cr1/3TaS2 are more dispersive than their counterparts in Cr1/3NbS2 and connect this result to bonding and orbital overlap in these materials. We also unambiguously distinguish exchange splitting from surface termination effects by studying the dependence of their photoemission spectra on polarization, temperature, and beam size. We find strong evidence that hybridization between intercalant and host lattice electronic states mediates the magnetic exchange interactions in these materials, suggesting that band engineering is a route toward tuning their spin textures. Overall, these results underscore how the modular nature of intercalated transition metal dichalcogenides translates variation in composition and electronic structure to complex magnetism., Comment: 46 pages, 18 figures, 5 tables
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- 2023
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25. Nature of charge density wave in kagome metal ScV6Sn6
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Lee, Seongyong, Won, Choongjae, Kim, Jimin, Yoo, Jonggyu, Park, Sudong, Denlinger, Jonathan, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Comin, Riccardo, Kang, Mingu, and Park, Jae-Hoon
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Kagome lattice materials offer a fertile ground to discover novel quantum phases of matter, ranging from unconventional superconductivity and quantum spin liquids to charge orders of various profiles. However, understanding the genuine origin of the quantum phases in kagome materials is often challenging, owing to the intertwined atomic, electronic, and structural degrees of freedom. Here, we combine angle-resolved photoemission spectroscopy, phonon mode calculation, and chemical doping to elucidate the driving mechanism of the root3*root3 charge order in a newly discovered kagome metal ScV6Sn6. In contrast to the case of the archetype kagome system AV3Sb5 (A= K, Rb, Cs), the van Hove singularities in ScV6Sn6 remain intact across the charge order transition, indicating a marginal role of the electronic instability from the V kagome lattice. Instead, we identified a three-dimensional band with dominant planar Sn character opening a large charge order gap of 260 meV and strongly reconstructing the Fermi surface. Our complementary phonon dispersion calculations further emphasize the role of the structural components other than the V kagome lattice by revealing the unstable planar Sn and Sc phonon modes associated to the root3*root3 phase. Finally, in the constructed phase diagram of Sc(V1-xCrx)6Sn6, the charge order remains robust in a wide doping range x = 0 ~ 0.10 against the Fermi level shift up to ~ 120 meV, further making the electronic scenarios such as Fermi surface or saddle point nesting unlikely. Our multimodal investigations demonstrate that the physics of ScV6Sn6 is fundamentally different from the canonical kagome metal AV3Sb5, uncovering a new mechanism to induce symmetry-breaking phase transition in kagome lattice materials.
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- 2023
26. magnetoARPES: Angle Resolved Photoemission Spectroscopy with Magnetic Field Control
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Ryu, Sae Hee, Reichenbach, Garett, Jozwiak, Chris M., Bostwick, Aaron, Richter, Peter, Seyller, Thomas, and Rotenberg, Eli
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Angle-Resolved Photoemission Spectroscopy (ARPES) is a premier technique for understanding the electronic excitations in conductive, crystalline matter, in which the induced photocurrent is collected and dispersed in energy and angle of emission to reveal the energy- and momentum-dependent single particle spectral function $A(\mathbf{k},\omega)$. So far, ARPES in a magnetic field has been precluded due to the need to preserve the electron paths between the sample and detector. In this paper we report progress towards "magnetoARPES", a variant of ARPES that can be conducted in a magnetic field. It is achieved by applying a microscopic probe beam ($\lesssim$ 10 $\mu$m ) to a thinned sample mounted upon a special sample holder that generates magnetic field confined to a thin layer near the sample surface. In this geometry we could produce ARPES in magnetic fields up to around $\pm$ 100 mT. The magnetic fields can be varied from purely in-plane to nearly purely out-of-plane, by scanning the probe beam across different parts of the device. We present experimental and simulated data for graphene to explore the aberrations induced by the magnetic field. These results demonstrate the viability of the magnetoARPES technique for exploring symmetry breaking effects in weak magnetic fields., Comment: 21 pages, 6 figures
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- 2023
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27. Strong Inter-valley Electron-Phonon Coupling in Magic-Angle Twisted Bilayer Graphene
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Chen, Cheng, Nuckolls, Kevin P., Ding, Shuhan, Miao, Wangqian, Wong, Dillon, Oh, Myungchul, Lee, Ryan L., He, Shanmei, Peng, Cheng, Pei, Ding, Li, Yiwei, Zhang, Shihao, Liu, Jianpeng, Liu, Zhongkai, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Li, Chu, Han, Xu, Pan, Ding, Dai, Xi, Liu, Chaoxing, Bernevig, B. Andrei, Wang, Yao, Yazdani, Ali, and Chen, Yulin
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Strongly Correlated Electrons - Abstract
The unusual properties of superconductivity in magic-angle twisted bilayer graphene (MATBG) have sparked enormous research interest. However, despite the dedication of intensive experimental efforts and the proposal of several possible pairing mechanisms, the origin of its superconductivity remains elusive. Here, using angle-resolved photoemission spectroscopy with micrometer spatial resolution, we discover replicas of the flat bands in superconducting MATBG unaligned with its hexagonal boron nitride (hBN) substrate, which are absent in non-superconducting MATBG aligned with the hBN substrate. Crucially, the replicas are evenly spaced in energy, separated by 150 +- 15 meV, signalling the strong coupling of electrons in MATBG to a bosonic mode of this energy. By comparing our observations to simulations, the formation of replicas is attributed to the presence of strong inter-valley electron-phonon coupling to a K-point phonon mode. In total, the observation of these replica flat bands and the corresponding phonon mode in MATBG could provide important information for understanding the origin and the unusual properties of its superconducting phase., Comment: 17 pages, 4 figures
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- 2023
28. On the effects of strain, defects, and interactions on the topological properties of HfTe5
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Jo, Na Hyun, Ashour, Omar A., Shu, Zhixue, Jozwiak, Chris, Bostwick, Aaron, Ryu, Sae Hee, Sun, Kai, Kong, Tai, Griffin, Sinead M., and Rotenberg, Eli
- Subjects
Condensed Matter - Materials Science - Abstract
Topological insulators are characterized by spin-momentum-locked massless surface states which are robust under various perturbations. Manipulating such surface states is a topic of vigorous research, as a possible route for the realization of emergent many-body physics in topological systems. Thus far, time-reversal symmetry breaking via Coulomb and magnetic perturbations has been a dominant approach for the tuning of topological states. However, the effect of the structural degrees of freedom on quasi-particle dynamics in topological materials remains elusive. In this work, we demonstrate a transition in HfTe5 between distinct topological phases as a function of either Te vacancy concentration or applied strain; these phases are characterized theoretically as a transition from strong to weak topological insulator and experimentally by a transition from sharp surface states and Dirac crossing to a Fermi-liquid-like quasiparticle state in which these surface-localized features are heavily suppressed. Although vacancies can result in various consequences such as scattering, doping, and structural distortions, we show that changes in the lattice constants play the foremost role in determining the electronic structure, self-energy, and topological states of HfTe5. Our results demonstrate the possibility of using both defect chemistry and strain as control parameters for topological phase transitions and associated many-body physics.
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- 2023
29. Small Fermi pockets intertwined with charge stripes and pair density wave order in a kagome superconductor
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Li, Hong, Oh, Dongjin, Kang, Mingu, Zhao, He, Ortiz, Brenden R, Oey, Yuzki, Fang, Shiang, Ren, Zheng, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Checkelsky, Joseph G., Wang, Ziqiang, Wilson, Stephen D., Comin, Riccardo, and Zeljkovic, Ilija
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Condensed Matter - Superconductivity ,Condensed Matter - Materials Science ,Condensed Matter - Strongly Correlated Electrons - Abstract
The kagome superconductor family AV3Sb5 (A=Cs, K, Rb) emerged as an exciting platform to study exotic Fermi surface instabilities. Here we use spectroscopic-imaging scanning tunneling microscopy (SI-STM) and angle-resolved photoemission spectroscopy (ARPES) to reveal how the surprising cascade of higher and lower-dimensional density waves in CsV3Sb5 is intimately tied to a set of small reconstructed Fermi pockets. ARPES measurements visualize the formation of these pockets generated by a 3D charge density wave transition. The pockets are connected by dispersive q* wave vectors observed in Fourier transforms of STM differential conductance maps. As the additional 1D charge order emerges at a lower temperature, q* wave vectors become substantially renormalized, signaling further reconstruction of the Fermi pockets. Remarkably, in the superconducting state, the superconducting gap modulations give rise to an in-plane Cooper pair-density-wave at the same q* wave vectors. Our work demonstrates the intrinsic origin of the charge-stripes and the pair-density-wave in CsV3Sb5 and their relationship to the Fermi pockets. These experiments uncover a unique scenario of how Fermi pockets generated by a parent charge density wave state can provide a favorable platform for the emergence of additional density waves.
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- 2023
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30. Synthesis and physical properties of a new layered ferromagnet, Cr1.21Te2
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Shu, Zhixue, Wang, Haozhe, Jo, Na Hyun, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Xie, Weiwei, and Kong, Tai
- Subjects
Condensed Matter - Materials Science - Abstract
Single crystals of a new layered compound, Cr1.21Te2, was synthesized via a vapor transport method. The crystal structure and physical properties were characterized by single crystal and powder x-ray diffraction, temperature- and field-dependent magnetization, zero-field heat capacity and angle-resolved photoemission spectroscopy. Cr1.21Te2, containing two Cr sites, crystalizes in a trigonal structure with a space group P-3 (No. 147). The Cr site in the interstitial layer is partially occupied. Physical property characterizations indicate that Cr1.21Te2 is metallic with hole pockets at the Fermi energy and undergoes a ferromagnetic phase transition at ~173 K. The magnetic moments align along the c-axis in the ferromagnetic state. Based on low temperature magnetization, the spin stiffness constant D and spin excitation gap $\Delta$ were estimated according to Bloch's law to be D = 99 $\pm$ 24 meV $\r{A}^2$ and $\Delta$ = 0.46 $\pm$ 0.33 meV, suggesting its possible application as a low dimensional ferromagnet., Comment: 6 figures
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- 2023
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31. Layer-Dependent Interaction Effects in the Electronic Structure of Twisted Bilayer Graphene Devices.
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Dale, Nicholas, Utama, M, Lee, Dongkyu, Leconte, Nicolas, Zhao, Sihan, Lee, Kyunghoon, Taniguchi, Takashi, Watanabe, Kenji, Jozwiak, Chris, Koch, Roland, Jung, Jeil, Wang, Feng, Lanzara, Alessandra, Rotenberg, Eli, and Bostwick, Aaron
- Subjects
ARPES ,band gap. ,electron−electron interaction ,moiré heterostructures ,symmetry-breaking ,twisted bilayer graphene - Abstract
Near the magic angle, strong correlations drive many intriguing phases in twisted bilayer graphene (tBG) including unconventional superconductivity and chern insulation. Whether correlations can tune symmetry breaking phases in tBG at intermediate (≳ 2°) twist angles remains an open fundamental question. Here, using ARPES, we study the effects of many-body interactions and displacement field on the band structure of tBG devices at an intermediate (3°) twist angle. We observe a layer- and doping-dependent renormalization of bands at the K points that is qualitatively consistent with moiré models of the Hartree-Fock interaction. We provide evidence of correlation-enhanced inversion symmetry-breaking, manifested by gaps at the Dirac points that are tunable with doping. These results suggest that electronic interactions play a significant role in the physics of tBG even at intermediate twist angles and present a new pathway toward engineering band structure and symmetry-breaking phases in moiré heterostructures.
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- 2023
32. Spectral evidence for unidirectional charge density wave in detwinned BaNi2As2
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Guo, Yucheng, Klemm, Mason, Oh, Ji Seop, Xie, Yaofeng, Lei, Bing-Hua, Moreschini, Luca, Chen, Cheng, Yue, Ziqin, Gorovikov, Sergey, Pedersen, Tor, Michiardi, Matteo, Zhdanovich, Sergey, Damascelli, Andrea, Denlinger, Jonathan, Hashimoto, Makoto, Lu, Donghui, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Mo, Sung-Kwan, Moore, Rob G, Kono, Junichiro, Birgeneau, Robert J, Singh, David J, Dai, Pengcheng, and Yi, Ming
- Subjects
Physical Sciences ,Condensed Matter Physics ,Chemical sciences ,Engineering ,Physical sciences - Abstract
In the iron-based superconductors, unconventional superconductivity emerges in proximity to intertwined electronic orders consisting of an electronic nematic order and a spin density wave (SDW). Recently, BaNi2As2, like its well-known iron-based analog BaFe2As2, has been discovered to host a symmetry-breaking structural transition but coupled to a unidirectional charge density wave (CDW) instead of SDW, providing a novel platform to study intertwined orders. Here, through a systematic angle-resolved photoemission spectroscopy study combined with a detwinning B1g uniaxial strain, we identify distinct spectral evidence of band evolution due to the structural transition as well as CDW-induced band folding. In contrast to the nematicity and spin density wave in BaFe2As2, the structural and CDW order parameters in BaNi2As2 are observed to be strongly coupled and do not separate in the presence of uniaxial strain. Furthermore, no nematic band splitting is resolved above the structural transition. Our measurements point to a likely lattice origin of the CDW order in BaNi2As2.
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- 2023
33. Tunable Van Hove Singularity without Structural Instability in Kagome Metal CsTi3Bi5
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Liu, Bo, Kuang, Min-Quan, Luo, Yang, Li, Yongkai, Hu, Cheng, Liu, Jiarui, Xiao, Qian, Zheng, Xiquan, Huai, Linwei, Peng, Shuting, Wei, Zhiyuan, Shen, Jianchang, Wang, Bingqian, Miao, Yu, Sun, Xiupeng, Ou, Zhipeng, Cui, Shengtao, Sun, Zhe, Hashimoto, Makoto, Lu, Donghui, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Moreschini, Luca, Lanzara, Alessandra, Wang, Yao, Peng, Yingying, Yao, Yugui, Wang, Zhiwei, and He, Junfeng
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Physical Sciences ,Condensed Matter Physics ,Mathematical Sciences ,Engineering ,General Physics ,Mathematical sciences ,Physical sciences - Abstract
In kagome metal CsV_{3}Sb_{5}, multiple intertwined orders are accompanied by both electronic and structural instabilities. These exotic orders have attracted much recent attention, but their origins remain elusive. The newly discovered CsTi_{3}Bi_{5} is a Ti-based kagome metal to parallel CsV_{3}Sb_{5}. Here, we report angle-resolved photoemission experiments and first-principles calculations on pristine and Cs-doped CsTi_{3}Bi_{5} samples. Our results reveal that the van Hove singularity (vHS) in CsTi_{3}Bi_{5} can be tuned in a large energy range without structural instability, different from that in CsV_{3}Sb_{5}. As such, CsTi_{3}Bi_{5} provides a complementary platform to disentangle and investigate the electronic instability with a tunable vHS in kagome metals.
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- 2023
34. Magnetism and charge density wave order in kagome FeGe
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Teng, Xiaokun, Oh, Ji Seop, Tan, Hengxin, Chen, Lebing, Huang, Jianwei, Gao, Bin, Yin, Jia-Xin, Chu, Jiun-Haw, Hashimoto, Makoto, Lu, Donghui, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Granroth, Garrett E, Yan, Binghai, Birgeneau, Robert J, Dai, Pengcheng, and Yi, Ming
- Subjects
Quantum Physics ,Physical Sciences ,Condensed Matter Physics ,Mathematical Sciences ,Fluids & Plasmas ,Mathematical sciences ,Physical sciences - Abstract
Electron correlations often lead to emergent orders in quantum materials, and one example is the kagome lattice materials where topological states exist in the presence of strong correlations between electrons. This arises from the features of the electronic band structure that are associated with the kagome lattice geometry: flat bands induced by destructive interference of the electronic wavefunctions, topological Dirac crossings and a pair of van Hove singularities. Various correlated electronic phases have been discovered in kagome lattice materials, including magnetism, charge density waves, nematicity and superconductivity. Recently, a charge density wave was discovered in the magnetic kagome FeGe, providing a platform for understanding the interplay between charge order and magnetism in kagome materials. Here we observe all three electronic signatures of the kagome lattice in FeGe using angle-resolved photoemission spectroscopy. The presence of van Hove singularities near the Fermi level is driven by the underlying magnetic exchange splitting. Furthermore, we show spectral evidence for the charge density wave as gaps near the Fermi level. Our observations point to the magnetic interaction-driven band modification resulting in the formation of the charge density wave and indicate an intertwined connection between the emergent magnetism and charge order in this moderately correlated kagome metal.
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- 2023
35. Hopping frustration-induced flat band and strange metallicity in a kagome metal
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Ye, Linda, primary, Fang, Shiang, additional, Kang, Mingu, additional, Kaufmann, Josef, additional, Lee, Yonghun, additional, John, Caolan, additional, Neves, Paul M., additional, Zhao, S. Y. Frank, additional, Denlinger, Jonathan, additional, Jozwiak, Chris, additional, Bostwick, Aaron, additional, Rotenberg, Eli, additional, Kaxiras, Efthimios, additional, Bell, David C., additional, Janson, Oleg, additional, Comin, Riccardo, additional, and Checkelsky, Joseph G., additional
- Published
- 2024
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36. Ideal Weak Topological Insulator and Protected Helical Saddle Points
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Oh, Ji Seop, Xu, Tianyi, Dhale, Nikhil, Li, Sheng, Lei, Chao, Yoon, Chiho, Liu, Wenhao, Huang, Jianwei, Wu, Hanlin, Hashimoto, Makoto, Lu, Donghui, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Lau, Chun Ning, Lv, Bing, Zhang, Fan, Birgeneau, Robert, and Yi, Ming
- Subjects
Condensed Matter - Materials Science - Abstract
The paradigm of classifying three-dimensional (3D) topological insulators into strong and weak ones (STI and WTI) opens the door for the discovery of various topological phases of matter protected by different symmetries and defined in different dimensions. However, in contrast to the vast realization of STIs, very few materials have been experimentally identified as being close to WTI. Even amongst those identified, none exists with topological surface states (TSS) exposed in a global bulk band gap that is stable at all temperatures. Here we report the design and observation of an ideal WTI in a quasi-one-dimensional (quasi-1D) bismuth halide, Bi$_{4}$I$_{1.2}$Br$_{2.8}$ (BIB). Via angle-resolved photoemission spectroscopy (ARPES), we identify that BIB hosts TSS on the (100)$\prime$ side surface in the form of two anisotropic $\pi$-offset Dirac cones (DCs) separated in momentum while topologically dark on the (001) top surface. The ARPES data fully determine a unique side-surface Hamiltonian and thereby identify two pairs of non-degenerate helical saddle points and a series of four Lifshitz transitions. The fact that both the surface Dirac and saddle points are in the global bulk band gap of 195 meV, combined with the small Dirac velocities, nontrivial spin texture, and the near-gap chemical potential, qualifies BIB to be not only an ideal WTI but also a fertile ground for topological many-body physics.
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- 2023
37. Phason-mediated interlayer exciton diffusion in WS2/WSe2 moir\'e heterostructure
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Rossi, Antonio, Zipfel, Jonas, Maity, Indrajit, Lorenzon, Monica, Francaviglia, Luca, Regan, Emma C., Zhang, Zuocheng, Nie, Jacob H., Barnard, Edward, Watanabe, Kenji, Taniguchi, Takashi, Rotenberg, Eli, Wang, Feng, Lischner, Johannes, Raja, Archana, and Weber-Bargioni, Alexander
- Subjects
Condensed Matter - Materials Science - Abstract
Moir\'e potentials in two-dimensional materials have been proven to be of fundamental importance to fully understand the electronic structure of van der Waals heterostructures, from superconductivity to correlated excitonic states. However, understanding how the moir\'e phonons, so-called phasons, affect the properties of the system still remains an uncharted territory. In this work, we demonstrate how phasons are integral to properly describing and understanding low-temperature interlayer exciton diffusion in WS2/WSe2 heterostructure. We perform photoluminescence (PL) spectroscopy to understand how the coupling between the layers, affected by their relative orientation, impacts the excitonic properties of the system. Samples fabricated with stacking angles of 0{\deg} and 60{\deg} are investigated taking into account the stacking angle dependence of the two common moir\'e potential profiles. Additionally, we present spatially and time-resolved exciton diffusion measurements, looking at the photoluminescence emission in a temperature range from 30 K to 250 K. An accurate potential for the two configurations are computed via density functional theory (DFT) calculations. Finally, we perform molecular dynamics simulation in order to visualize the phasons motion, estimating the phason speed at different temperatures, providing novel insights into the mechanics of exciton propagation at low temperatures that cannot be explained within the frame of classical exciton diffusion alone., Comment: A. Rossi, J. Zipfel, and I. Maity contributed equally
- Published
- 2023
38. WS$_2$ Band Gap Renormalization Induced by Tomonaga Luttinger Liquid Formation in Mirror Twin Boundaries
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Rossi, Antonio, Thomas, John C., Küchle, Johannes T., Barré, Elyse, Yu, Zhuohang, Zhou, Da, Kumari, Shalini, Tsai, Hsin-Zon, Wong, Ed, Jozwiak, Chris, Bostwick, Aaron, Robinson, Joshua A., Terrones, Mauricio, Raja, Archana, Schwartzberg, Adam, Ogletree, D. Frank, Neaton, Jeffrey B., Crommie, Michael F., Allegretti, Francesco, Auwärter, Willi, Rotenberg, Eli, and Weber-Bargioni, Alexander
- Subjects
Condensed Matter - Materials Science - Abstract
Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of mirror twin boundaries (MTBs) hosting a Fermi liquid or a TLL have suggested a dependence on the underlying substrate, however, unveiling the physical details of electronic contributions from the substrate require cross-correlative investigation. Here, we study TLL formation in MTBs within defectively engineered WS$_2$ atop graphene, where band structure and the atomic environment is visualized with nano angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and scanning tunneling spectroscopy, and non-contact atomic force microscopy. Correlations between the local density of states and electronic band dispersion elucidated the electron transfer from graphene into a TLL hosted by MTB defects. We find that MTB defects can be substantially charged at a local level, which drives a band gap shift by $\sim$0.5 eV., Comment: Main text is 13 pages, 4 figures; Supplementary text is 14 pages, 11 figures
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- 2023
39. Nanoscale view of engineered massive Dirac quasiparticles in lithographic superstructures
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Jones, Alfred J. H., Gammelgaard, Lene, Sauer, Mikkel O., Biswas, Deepnarayan, Koch, Roland J., Jozwiak, Chris, Rotenberg, Eli, Bostwick, Aaron, Watanabe, Kenji, Taniguchi, Takashi, Dean, Cory R., Jauho, Antti-Pekka, Bøggild, Peter, Pedersen, Thomas G., Jessen, Bjarke S., and Ulstrup, Søren
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Massive Dirac fermions are low-energy electronic excitations characterized by a hyperbolic band dispersion. They play a central role in several emerging physical phenomena such as topological phase transitions, anomalous Hall effects and superconductivity. This work demonstrates that massive Dirac fermions can be controllably induced by lithographically patterning superstructures of nanoscale holes in a graphene device. Their band dispersion is systematically visualized using angle-resolved photoemission spectroscopy with nanoscale spatial resolution. A linear scaling of effective mass with feature sizes is discovered, underlining the Dirac nature of the superstructures. In situ electrostatic doping dramatically enhances the effective hole mass and leads to the direct observation of an electronic band gap that results in a peak-to-peak band separation of (0.64 $\pm$ 0.03) eV, which is shown via first-principles calculations to be strongly renormalized by carrier-induced screening. The presented methodology outlines a new approach for band structure engineering guided by directly viewing structurally- and electrically-tunable massive Dirac quasiparticles in lithographic superstructures at the nanoscale., Comment: 37 pages, 12 figures (includes supporting information). A revised version has been published in ACS Nano
- Published
- 2022
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40. Topological band inversion in HgTe(001): surface and bulk signatures from photoemission
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Vidal, Raphael C., Marini, Giovanni, Lunczer, Lukas, Moser, Simon, Fürst, Lena, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Gould, Charles, Buhmann, Hartmut, Beugeling, Wouter, Sangiovanni, Giorgio, Di Sante, Domenico, Profeta, Gianni, Molenkamp, Laurens W., Bentmann, Hendrik, and Reinert, Friedrich
- Subjects
Condensed Matter - Materials Science - Abstract
HgTe is a versatile topological material and has enabled the realization of a variety of topological states, including two- and three-dimensional (3D) topological insulators and topological semimetals. Nevertheless, a quantitative understanding of its electronic structure remains challenging, in particular due to coupling of the Te 5p-derived valence electrons to Hg 5d core states at shallow binding energy. We present a joint experimental and theoretical study of the electronic structure in strained HgTe(001) films in the 3D topological-insulator regime, based on angle-resolved photoelectron spectroscopy and density functional theory. The results establish detailed agreement in terms of (i) electronic band dispersions and orbital symmetries, (ii) surface and bulk contributions to the electronic structure, and (iii) the importance of Hg 5d states in the valence-band formation. Supported by theory, our experiments directly image the paradigmatic band inversion in HgTe, underlying its non-trivial band topology.
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- 2022
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41. Topological band inversion in HgTe(001): Surface and bulk signatures from photoemission
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Vidal, Raphael C, Marini, Giovanni, Lunczer, Lukas, Moser, Simon, Fürst, Lena, Issing, Julia, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Gould, Charles, Buhmann, Hartmut, Beugeling, Wouter, Sangiovanni, Giorgio, Di Sante, Domenico, Profeta, Gianni, Molenkamp, Laurens W, Bentmann, Hendrik, and Reinert, Friedrich
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Physical Sciences ,Condensed Matter Physics ,Chemical sciences ,Engineering ,Physical sciences - Abstract
HgTe is a versatile topological material and has enabled the realization of a variety of topological states, including two- and three-dimensional (3D) topological insulators and topological semimetals. Nevertheless, a quantitative understanding of its electronic structure remains challenging, in particular, due to coupling of the Te 5p-derived valence electrons to Hg 5d core states at shallow binding energy. We present a joint experimental and theoretical study of the electronic structure in strained HgTe(001) films in the 3D topological-insulator regime, based on angle-resolved photoelectron spectroscopy and density functional theory. The results establish detailed agreement in terms of: (i) electronic band dispersions and orbital symmetries, (ii) surface and bulk contributions to the electronic structure, and (iii) the importance of Hg 5d states in the valence-band formation. Supported by theory, our experiments directly image the paradigmatic band inversion in HgTe, underlying its nontrivial band topology.
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- 2023
42. Antiferromagnetic metal phase in an electron-doped rare-earth nickelate
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Song, Qi, Doyle, Spencer, Pan, Grace A., Baggari, Ismail El, Segedin, Dan Ferenc, Carrizales, Denisse Cordova, Nordlander, Johanna, Tzschaschel, Christian, Ehrets, James R., Hasan, Zubia, El-Sherif, Hesham, Krishna, Jyoti, Hanson, Chase, LaBollita, Harrison, Bostwick, Aaron, Jozwiak, Chris, Rotenberg, Eli, Xu, Su-Yang, Lanzara, Alessandra, N'Diaye, Alpha T., Heikes, Colin A., Liu, Yaohua, Paik, Hanjong, Brooks, Charles M., Pamuk, Betul, Heron, John T., Shafer, Padraic, Ratcliff, William D., Botana, Antia S., Moreschini, Luca, and Mundy, Julia A.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Long viewed as passive elements, antiferromagnetic materials have emerged as promising candidates for spintronic devices due to their insensitivity to external fields and potential for high-speed switching. Recent work exploiting spin and orbital effects has identified ways to electrically control and probe the spins in metallic antiferromagnets, especially in noncollinear or noncentrosymmetric spin structures. The rare earth nickelate NdNiO3 is known to be a noncollinear antiferromagnet where the onset of antiferromagnetic ordering is concomitant with a transition to an insulating state. Here, we find that for low electron doping, the magnetic order on the nickel site is preserved while electronically a new metallic phase is induced. We show that this metallic phase has a Fermi surface that is mostly gapped by an electronic reconstruction driven by the bond disproportionation. Furthermore, we demonstrate the ability to write to and read from the spin structure via a large zero-field planar Hall effect. Our results expand the already rich phase diagram of the rare-earth nickelates and may enable spintronics applications in this family of correlated oxides., Comment: 25 pages, 4 figures
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- 2022
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43. Electronic band structure changes across the antiferromagnetic phase transition of exfoliated MnPS$_3$ probed by $\mu$-ARPES
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Strasdas, Jeff, Pestka, Benjamin, Rybak, Milosz, Budniak, Adam K., Leuth, Niklas, Boban, Honey, Feyer, Vitaliy, Cojocariu, Iulia, Baranowski, Daniel, Avila, José, Dudin, Pavel, Bostwick, Aaron, Jozwiak, Chris, Rotenberg, Eli, Autieri, Carmine, Amouyal, Yaron, Plucinski, Lukasz, Lifshitz, Efrat, Birowska, Magdalena, and Morgenstern, Markus
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Other Condensed Matter ,J.2 - Abstract
Exfoliated magnetic 2D materials enable versatile tuning of magnetization, e.g., by gating or providing proximity-induced exchange interaction. However, their electronic band structure after exfoliation has not been probed, most likely due to their photochemical sensitivity. Here, we provide micron-scale angle-resolved photoelectron spectroscopy of the exfoliated intralayer antiferromagnet MnPS$_3$ above and below the N\'{e}el temperature down to one monolayer. The favorable comparison with density functional theory calculations enables to identify the orbital character of the observed bands. Consistently, we find pronounced changes across the N\'{e}el temperature for bands that consist of Mn 3d and 3p levels of adjacent S atoms. The deduced orbital mixture indicates that the superexchange is relevant for the magnetic interaction. There are only minor changes between monolayer and thicker films demonstrating the predominant 2D character of MnPS$_3$. The novel access is transferable to other MPX$_3$ materials (M: transition metal, P: phosphorus, X: chalcogenide) providing a multitude of antiferromagnetic arrangements., Comment: 26 pages, 17 figures
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- 2022
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44. Visualization of Strain-Induced Landau Levels in a Graphene - Black Phosphorus Heterostructure
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Vu, Thi-Hai-Yen, Lyu, Pin, Jo, Na Hyun, Trang, Chi Xuan, Li, Qile, Bostwick, Aaron, Jozwiak, Chris, Rotenberg, Eli, Lu, Jiong, Fuhrer, Michael S., and Edmonds, Mark T.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Strain-induced pseudo magnetic fields offer the possibility of realizing zero magnetic field Quantum Hall effect in graphene, possibly up to room temperature, representing a promising avenue for lossless charge transport applications. Strain engineering on graphene has been achieved via random nanobubbles or artificial nanostructures on the substrate, but the highly localized and non-uniform pseudomagnetic fields can make spectroscopic probes of electronic structure difficult. Heterostructure engineering offers an alternative approach: By stacking graphene on top of another van der Waals material with large lattice mismatch at a desired twist angle, it is possible to generate large strain-induced pseudo magnetic fields uniformly over the entire heterostructure. Here, we report using nano-angle resolved photoemission spectroscopy (nano-ARPES) to probe the electronic bandstructure of a graphene/black phosphorus heterostructure (G/BP). By directly measuring the iso-energy contours of graphene and black phosphorus we determine a twist angle of 20-degrees in our heterostructure. High-resolution nano-ARPES of the graphene bands near the Fermi level reveals the emergence of flat bands located within the Dirac cone. The spacing of the flat bands is consistent with Landau level formation in graphene, and corresponds to a pseudo-field of 11.36 T. Our work provides a new way to study quantum Hall phases induced by strain in 2D materials and heterostructures.
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- 2022
45. Direct visualization and control of SrOx segregation on semiconducting Nb doped SrTiO3 (100) surface
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Yoo, Hyang Keun, Schwarz, Daniel, Ulstrup, Soren, Kim, Woojin, Jozwiak, Chris, Bostwick, Aaron, Noh, Tae Won, Rotenberg, Eli, and Chang, Young Jun
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Condensed Matter - Materials Science - Abstract
We investigated how SrOx segregates on a Nb doped SrTiO3 (100) surface by in air annealing. Using atomic force and photoemission electron microscopes, we can directly visualize the morphology and the electronic phase changes with SrOx segregation. SrOx islands less than 2 micron meter in size and 1-5 unit cells thick nucleate first and grow in a labyrinth domain pattern. After prolonged annealing, SrOx forms a ~10 nm thick film. We show that the domain pattern can be controlled by introducing a surface miscut angle of SrTiO3. Additionally, the segregated SrOx has a lower work function, compared to that of SrTiO3. These results suggest that the control and tunability of SrOx segregation is applicable to the design of a new functional electronic devices in the semiconducting SrTiO3 based heterostructure.
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- 2022
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46. Intertwined magnetism and charge density wave order in kagome FeGe
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Teng, Xiaokun, Oh, Ji Seop, Tan, Hengxin, Chen, Lebing, Huang, Jianwei, Gao, Bin, Yin, Jia-Xin, Chu, Jiun-Haw, Hashimoto, Makoto, Lu, Donghui, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Granroth, Garrett E., Yan, Binghai, Birgeneau, Robert J., Dai, Pengcheng, and Yi, Ming
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Condensed Matter - Strongly Correlated Electrons - Abstract
Electron correlations often lead to emergent orders in quantum materials. Kagome lattice materials are emerging as an exciting platform for realizing quantum topology in the presence of electron correlations. This proposal stems from the key signatures of electronic structures associated with its lattice geometry: flat band induced by destructive interference of the electronic wavefunctions, topological Dirac crossing, and a pair of van Hove singularities (vHSs). A plethora of correlated electronic phases have been discovered amongst kagome lattice materials, including magnetism, charge density wave (CDW), nematicity, and superconductivity. These materials can be largely organized into two types: those that host magnetism and those that host CDW order. Recently, a CDW order has been discovered in the magnetic kagome FeGe, providing a new platform for understanding the interplay between CDW and magnetism. Here, utilizing angle-resolved photoemission spectroscopy, we observe all three types of electronic signatures of the kagome lattice: flat bands, Dirac crossings, and vHSs. From both the observation of a temperature-dependent shift of the vHSs towards the Fermi level as well as guidance via first-principle calculations, we identify the presence of the vHSs near the Fermi level (EF) to be driven by the development of underlying magnetic exchange splitting. Furthermore, we show spectral evidence for the CDW order as gaps that open on the near-EF vHS bands, as well as evidence of electron-phonon coupling from a kink on the vHS band together with phonon hardening observed by inelastic neutron scattering. Our observation points to the magnetic interaction-driven band modification resulting in the formation of the CDW order, indicating an intertwined connection between the emergent magnetism and vHS charge order in this moderately-correlated kagome metal., Comment: submitted on April 22, 2022
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- 2022
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47. Three-dimensional flat bands in pyrochlore metal CaNi2
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Wakefield, Joshua P., Kang, Mingu, Neves, Paul M., Oh, Dongjin, Fang, Shiang, McTigue, Ryan, Frank Zhao, S. Y., Lamichhane, Tej N., Chen, Alan, Lee, Seongyong, Park, Sudong, Park, Jae-Hoon, Jozwiak, Chris, Bostwick, Aaron, Rotenberg, Eli, Rajapitamahuni, Anil, Vescovo, Elio, McChesney, Jessica L., Graf, David, Palmstrom, Johanna C., Suzuki, Takehito, Li, Mingda, Comin, Riccardo, and Checkelsky, Joseph G.
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- 2023
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48. Anomalous excitonic phase diagram in band-gap-tuned Ta2Ni(Se,S)5
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Chen, Cheng, primary, Tang, Weichen, additional, Chen, Xiang, additional, Kang, Zhibo, additional, Ding, Shuhan, additional, Scott, Kirsty, additional, Wang, Siqi, additional, Li, Zhenglu, additional, Ruff, Jacob P. C., additional, Hashimoto, Makoto, additional, Lu, Dong-Hui, additional, Jozwiak, Chris, additional, Bostwick, Aaron, additional, Rotenberg, Eli, additional, da Silva Neto, Eduardo H., additional, Birgeneau, Robert J., additional, Chen, Yulin, additional, Louie, Steven G., additional, Wang, Yao, additional, and He, Yu, additional
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- 2023
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49. A substitutional quantum defect in WS2 discovered by high-throughput computational screening and fabricated by site-selective STM manipulation
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Thomas, John, primary, Chen, Wei, additional, Xiong, Yihuang, additional, Barker, Bradford, additional, Zhou, Junze, additional, Chen, Weiru, additional, Rossi, Antonio, additional, Kelly, Nolan, additional, Yu, Zhuohang, additional, Zhou, Da, additional, Kumari, Shalini, additional, Barnard, Edward, additional, Robinson, Joshua, additional, Terrones, Mauricio, additional, Schwartzberg, Adam, additional, Ogletree, D. Frank, additional, Rotenberg, Eli, additional, Noack, Marcus, additional, Griffin, Sinéad, additional, Raja, Archana, additional, Strubbe, David, additional, Rignanese, Gian-Marco, additional, Weber-Bargioni, Alexander, additional, and Hautier, Geoffroy, additional
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- 2023
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50. Ideal weak topological insulator and protected helical saddle points
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Oh, Ji Seop, primary, Xu, Tianyi, additional, Dhale, Nikhil, additional, Li, Sheng, additional, Lei, Chao, additional, Yoon, Chiho, additional, Liu, Wenhao, additional, Huang, Jianwei, additional, Wu, Hanlin, additional, Hashimoto, Makoto, additional, Lu, Donghui, additional, Jozwiak, Chris, additional, Bostwick, Aaron, additional, Rotenberg, Eli, additional, Lau, Chun Ning, additional, Lv, Bing, additional, Zhang, Fan, additional, Birgeneau, Robert J., additional, and Yi, Ming, additional
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- 2023
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