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127 results on '"Kardynal B"'

1. Resonant Raman scattering of surface phonon polaritons mediated by excitons in WSe$_2$ films

Author

Zhou, L., Wirth, K., Bui, M. N., Rani, R., Grützmacher, D., Taubner, T., and Kardynał, B. E.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Surface phonon-polaritons propagating along interfaces of polar dielectrics coexist with excitons in many van der Waals heterostructures, so understanding their mutual interactions is of great interest. Here, we investigate the type I surface phonon polariton of hBN via low-temperature resonant-Raman spectroscopy in hBN/WSe2 heterostructures. The resonantly enhanced hBN surface phonon polariton (SPhP) Raman signal, when laser energy is such that the scattered photons have energy close to that of the WSe2 excitons, enables detailed characterization of type I SPhP in hBN even when hBN is one monolayer thick. We find that the measured bandwidth of the SPhP Raman signal depends on the thicknesses of the hBN layer. We are able explain the experimental data using transfer matrix method simulations of SPhP dispersions providing that we assume the Raman scattering to be momentum non-conserving, as could be the case if localized WSe2 exciton states participated in the process. We further show that resonant Raman scattering from SiO2 SPhP can also be mediated by WSe$_2$., Comment: 23 pages, 11 figures

Published
2024

2. An avalanche-photodiode-based photon-number-resolving detector

Author

Kardynal, B. E., Yuan, Z. L., and Shields, A. J.

Subjects
Quantum Physics, Condensed Matter - Other Condensed Matter, Physics - Instrumentation and Detectors, Physics - Optics
Abstract

Avalanche photodiodes are widely used as practical detectors of single photons.1 Although conventional devices respond to one or more photons, they cannot resolve the number in the incident pulse or short time interval. However, such photon number resolving detectors are urgently needed for applications in quantum computing,2-4 communications5 and interferometry,6 as well as for extending the applicability of quantum detection generally. Here we show that, contrary to current belief,3,4 avalanche photodiodes are capable of detecting photon number, using a technique to measure very weak avalanches at the early stage of their development. Under such conditions the output signal from the avalanche photodiode is proportional to the number of photons in the incident pulse. As a compact, mass-manufactured device, operating without cryogens and at telecom wavelengths, it offers a practical solution for photon number detection., Comment: 12 pages, 4 figures

Published
2008
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3. High speed single photon detection in the near-infrared

Author

Yuan, Z. L., Kardynal, B. E., Sharpe, A. W., and Shields, A. J.

Subjects
Quantum Physics, Physics - Instrumentation and Detectors, Physics - Optics
Abstract

InGaAs avalanche photodiodes (APDs) are convenient for single photon detection in the near-infrared (NIR) including the fibre communication bands (1.31/1.55 $\mu$m). However, to suppress afterpulse noise due to trapped avalanche charge, they must be gated with MHz repetition frequencies, thereby severely limiting the count rate in NIR applications. Here we show gating frequencies for InGaAs-APDs well beyond 1 GHz. Using a self-differencing technique to sense much weaker avalanches, we reduce drastically afterpulse noise. At 1.25 GHz, we obtain a detection efficiency of 10.8% with an afterpulse probability of 6.16%. In addition, the detector features low jitter (55 ps) and a count rate of 100 MHz.

Published
2007
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4. Metal-Insulator oscillations in a Two-dimensional Electron-Hole system

Author

Nicholas, R. J., Takashina, K., Lakrimi, M., Kardynal, B., Khym, S., Mason, N. J., Symons, D. M., Maude, D. K., and Portal, J. C.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The electrical transport properties of a bipolar InAs/GaSb system have been studied in magnetic field. The resistivity oscillates between insulating and metallic behaviour while the quantum Hall effect shows a digital character oscillating from 0 to 1 conducatance quantum e^2/h. The insulating behaviour is attributed to the formation of a total energy gap in the system. A novel looped edge state picture is proposed associated with the appearance of a voltage between Hall probes which is symmetric on magnetic field reversal., Comment: 4 pages, 5 Postscript figures: revised version

Published
1999
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7. Low-energy Se ion implantation in MoS2 monolayers

Author

Bui, M. N. (Minh N.), Rost, S. (Stefan), Auge, M. (Manuel), Tu, J.-S. (Jhih-Sian), Zhou, L. (Lanqing), Aguilera, I. (Irene), Blügel, S. (Stefan), Ghorbani-Asl, M. (Mahdi), Krasheninnikov, A. V. (Arkady V.), Hashemi, A. (Arsalan), Komsa, H.-P. (Hannu-Pekka), Jin, L. (Lei), Kibkalo, L. (Lidia), O’Connell, E. N. (Eoghan N.), Ramasse, Q. M. (Quentin M.), Bangert, U. (Ursel), Hofsäss, H. C. (Hans C.), Grützmacher, D. (Detlev), Kardynal, B. E. (Beata E.), Bui, M. N. (Minh N.), Rost, S. (Stefan), Auge, M. (Manuel), Tu, J.-S. (Jhih-Sian), Zhou, L. (Lanqing), Aguilera, I. (Irene), Blügel, S. (Stefan), Ghorbani-Asl, M. (Mahdi), Krasheninnikov, A. V. (Arkady V.), Hashemi, A. (Arsalan), Komsa, H.-P. (Hannu-Pekka), Jin, L. (Lei), Kibkalo, L. (Lidia), O’Connell, E. N. (Eoghan N.), Ramasse, Q. M. (Quentin M.), Bangert, U. (Ursel), Hofsäss, H. C. (Hans C.), Grützmacher, D. (Detlev), and Kardynal, B. E. (Beata E.)

Abstract

In this work, we study ultra-low energy implantation into MoS2 monolayers to evaluate the potential of the technique in two-dimensional materials technology. We use 80Se+ ions at the energy of 20 eV and with fluences up to 5.0·1014 cm−2. Raman spectra of the implanted films show that the implanted ions are predominantly incorporated at the sulfur sites and MoS2−2xSe2x alloys are formed, indicating high ion retention rates, in agreement with the predictions of molecular dynamics simulations of Se ion irradiation on MoS2 monolayers. We found that the ion retention rate is improved when implantation is performed at an elevated temperature of the target monolayers. Photoluminescence spectra reveal the presence of defects, which are mostly removed by post-implantation annealing at 200 °C, suggesting that, in addition to the Se atoms in the substitutional positions, weakly bound Se adatoms are the most common defects introduced by implantation at this ion energy.

Published
2022

8. Low-energy Se ion implantation in MoS₂ monolayers

Author

Bui, M. N., Rost, S., Auge, M., Tu, J.-S., Zhou, L., Aguilera, I., Blügel, S., (0000-0003-3060-4369) Ghorbani Asl, M., (0000-0003-0074-7588) Krasheninnikov, A., Hashemi, A., Komsa, H.-P., Jin, L., Kibkalo, L., O’Connell, E. N., Ramasse, Q. M., Bangert, U., Hofsäss, H. C., Grützmacher, D., Kardynal, B. E., Bui, M. N., Rost, S., Auge, M., Tu, J.-S., Zhou, L., Aguilera, I., Blügel, S., (0000-0003-3060-4369) Ghorbani Asl, M., (0000-0003-0074-7588) Krasheninnikov, A., Hashemi, A., Komsa, H.-P., Jin, L., Kibkalo, L., O’Connell, E. N., Ramasse, Q. M., Bangert, U., Hofsäss, H. C., Grützmacher, D., and Kardynal, B. E.

Abstract

In this work, we study ultra-low energy implantation into MoS₂ monolayers to evaluate the potential of the technique in two-dimensional materials technology. We use 80 Se⁺ ions at the energy of 20 eV and with fluences up to 5.0 · 10¹⁴ cm⁻². Raman spectra of the implanted films show that the implanted ions are predominantly incorporated at the sulfur sites and MoS₂₋₂ₓ Se₂ₓ alloys are formed, indicating high ion retention rates, in agreement with the predictions of molecular dynamics simulations of Se ion irradiation on MoS₂ monolayers. We found that the ion retention rate is improved when implantation is performed at an elevated temperature of the target monolayers. Photoluminescence spectra reveal the presence of defects, which are mostly removed by post-implantation annealing at 200 ˚C, suggesting that, in addition to the Se atoms in the substitutional positions, weakly bound Se adatoms are the most common defects introduced by implantation at this ion energy.

Published
2022

10. Poster: Spin-Related Phenomena

Author

Djieutedjeu, Honore, primary, Ranmohotti, Kulugammana G. S., additional, Takas, Nathan J., additional, Makongo, Julien P. A., additional, Zhou, Xiaoyuan, additional, Uher, Ctirad, additional, Haldolaarachchige, N., additional, Young, D. P., additional, Poudeu, Pierre F. P., additional, Kirilmaz, O., additional, Paul, M., additional, Müller, A., additional, Kufer, D., additional, Sing, M., additional, Claessen, R., additional, Brück, S., additional, Praetorius, C., additional, Fauth, K., additional, Kamp, M., additional, Audehm, P., additional, Goering, E., additional, Verbeeck, J., additional, Tian, H., additional, Van Tendeloo, G., additional, Ingle, N. J. C., additional, Przybylski, M., additional, Gorgoi, M., additional, Iván, Bernal, additional, Silvia, Gallego, additional, Kashid, Vikas, additional, Shah, Vaishali, additional, Salunke, H. G., additional, Mokrousov, Y., additional, Blügel, S., additional, Fuchs, Dirk, additional, Merz, Michael, additional, Dieterle, Levin, additional, Uebe, Stefan, additional, Nagel, Peter, additional, Schuppler, Stefan, additional, Gerthsen, Dagmar, additional, von Löhneysen, Hilbert, additional, Togawa, Yoshihiko, additional, Koyama, Tsukasa, additional, Mori, Shigeo, additional, Kousaka, Yusuke, additional, Akimitsu, Jun, additional, Nishihara, Sadafumi, additional, Inoue, Katsuya, additional, Ovchinnikov, Alexander, additional, Kishine, Jun-Ichiro, additional, Mahendiran, Ramanathan, additional, Xiao, Y., additional, Su, Y., additional, Nandi, S., additional, Price, S., additional, Brückel, Th., additional, Zimmermann, B., additional, Mavropoulos, P., additional, Heers, S., additional, Long, N. H., additional, Sasioglu, Ersoy, additional, Friedrich, Christoph, additional, Blügel, Stefan, additional, Moshnyaga, V., additional, Binek, Christian, additional, He, Xi, additional, Wang, Yi, additional, Wu, N., additional, Wysocki, Aleksander L., additional, Komesu, Takashi, additional, Lanke, Uday, additional, Caruso, Anthony N., additional, Vescovo, Elio, additional, Belashchenko, Kirill D., additional, Dowben, Peter A., additional, Sando, Daniel, additional, Agbelele, Arsène, additional, Daumont, Christophe, additional, Juraszek, Jean, additional, Cazayous, Maximilien, additional, Infante, Ingrid, additional, Ren, Wei, additional, Lisenkov, Sergey, additional, Carretero, Cécile, additional, Bellaiche, Laurent, additional, Dkhil, Brahim, additional, Barthélémy, Agnès, additional, Bibes, Manuel, additional, Zhou, Xianzhong, additional, Mennig, Julius, additional, Matthes, Frank, additional, Bürgler, Daniel E., additional, Schneider, Claus M., additional, Herpers, Anja, additional, Park, Chanwoo, additional, Egoavil, Ricardo, additional, Verbeeck, Jo, additional, Dittmann, Regina, additional, Kurbakov, A. I., additional, Abdel-Latif, I. A., additional, Trunov, V. A., additional, Habermeier, H. U., additional, Al-Hajry, A., additional, Malyshev, A. L., additional, Ulyanov, V. A., additional, Kishine, J., additional, Ovchinnikov, A. S., additional, Proskurin, I. V., additional, Saltzmann, T., additional, Rieß, S., additional, Kampmeier, J., additional, Mussler, G., additional, Stoica, T., additional, Kardynal, B., additional, Simon, U., additional, Hardtdegen, H., additional, Felser, C., additional, Müchler, L., additional, Chadov, S., additional, Yan, B., additional, Kübler, J., additional, Zhang, HJ, additional, Zhang, SC, additional, Pauly, Christian, additional, Bihlmayer, Gustav, additional, Liebmann, Marcus, additional, Grob, Martin, additional, Georgi, Alexander, additional, Subramaniam, Dinesh, additional, Scholz, Markus, additional, Sánchez-Barriga, Jaime, additional, Varykhalov, Andrei, additional, Rader, Oliver, additional, Morgenstern, Markus, additional, Aguilera, Irene, additional, Rushchanskii, Konstantin Z., additional, Garcia-Sanchez, Felipe, additional, Hertel, Riccardo, additional, Ležaić, Marjana, additional, Goian, Veronica, additional, Kamba, Stanislav, additional, Kadlec, Christelle, additional, Kužel, Petr, additional, Pisarev, Roman V., additional, Foschini, C. R., additional, Moura, F., additional, Ramirez, M. A., additional, Varela, J. A., additional, Longo, E., additional, Simões, A. Z., additional, Iusan, Diana, additional, Yamauchi, Kunihiko, additional, Delaney, Kris, additional, Picozzi, Silvia, additional, Yu, Jian, additional, Zhang, Linlin, additional, Hou, Xianbo, additional, Yedra, Lluís., additional, Estradé, Sònia, additional, Pellicer, Eva., additional, Cabo, Moisés, additional, López-Ortega, Alberto, additional, Estrader, Marta, additional, Nogués, Josep, additional, Baró, Dolors, additional, Saghi, Zineb, additional, Midgley, Paul A., additional, Peiró, Francesca, additional, Schena, Timo, additional, and Zimmermann, Bernd, additional

Published
2013
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11. Off-axis electron holography of exchange-biased CoFe/FeMn patterned nanostructures

Author

Dunin-Borkowski, R.E., McCartney, M.R., Kardynal, B., Scheinfien, M.R., Smith, David J., and Parkin S.S.P.

Subjects
Iron compounds -- Electric properties, Holography -- Usage, Physics
Abstract

Off-axis electron holography and micromagnetic simulations are used to investigate magnetization reversal mechanisms and remanent states in exchange-biased submicron Co(sub 84)Fe(sub 16)/Fe(sub 54)Mn(sub 46) patterned elements. Using an interface exchange field that had a fixed amplitude and direction in the simulations provided a good fit to the experimental data, and small disagreements were attributed to structural imperfections.

Published
2001

12. Interlayer coupling within individual submicron magnetic elements

Author

Smith, David J., Dunin-Borkowski, R.E., McCartney, M.R., Kardynal, B., and Scheinfein, M.R.

Subjects
Aluminum compounds -- Magnetic properties, Iron compounds -- Magnetic properties, Physics
Abstract

Off-axis electron holography and micromagnetic simulations are used to investigate the interlayer coupling and magnetization reversal of patterned, submicron Co/Au/Ni nanostructures, shaped as diamonds, ellipses, and rectangles. The study shows that antiferromagnetic coupling between the ferromagnetic layers, attributed to the strong Co demagnetization field, was visualized directly and simulated hysteresis loops showed reasonable agreement with experimental results.

Published
2000

13. Magnetic interactions within patterned cobalt nanostructures using off-axis electron holography

Author

Dunin-Borkowski, R.E., McCartney, M.R., Kardynal, B., and Smith, David J.

Subjects
Magnets -- Research, Magnetization -- Research, Hysteresis -- Research, Cobalt -- Magnetic properties, Physics
Abstract

The magnetization reversal characteristics of submicron-sized patterned Co elements were investigated through off-axis electron holography. The samples were immersed in magnetic fields in situ to find out the hysteresis loops of individual elements and the interactions between closely spaced elements. Findings suggested that the formation of remanent states from various stages in a magnetization reversal loop has fundamental importance for the design of magnetic elements for device applications.

Published
1998

15. Visibility of two-dimensional layered materials on various substrates.

Author

Müller, M. R., Gumprich, A., Ecik, E., Kallis, K. T., Winkler, F., Kardynal, B., Petrov, I., Kunze, U., and Knoch, J.

Subjects
SUBSTRATES (Materials science), TWO-dimensional materials (Nanotechnology), GRAPHENE, BORON nitride, HETEROSTRUCTURES, MICROSCOPY, ATOMIC force microscopy
Abstract

For the investigation of 2D layered materials such as graphene, transition-metal dichalcogenides, boron nitride, and their heterostructures, dedicated substrates are required to enable unambiguous identification through optical microscopy. A systematic study is conducted, focusing on various 2D layered materials and substrates. The simulated colors are displayed and compared with microscopy images. Additionally, the issue of defining an appropriate index for measuring the degree of visibility is discussed. For a wide range of substrate stacks, layer thicknesses for optimum visibility are given along with the resulting sRGB colors. Further simulations of customized stacks can be conducted using our simulation tool, which is available for download and contains a database featuring a wide range of materials. [ABSTRACT FROM AUTHOR]

Published
2015
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25. Insulating states of a 2-dimensional electron-hole system in high magnetic field

Author

Takashina, K, Nicholas, RJ, Kardynal, B, Mason, N, Maude, D, and Portal, JC

Subjects
Condensed Matter::Mesoscopic Systems and Quantum Hall Effect
Abstract

We find that an InAs/GaSb based electron-hole system exhibits insulating behaviour when the numbers of occupied electron and hole Landau levels are equal. In this insulating state, the Hall resistance becomes symmetric under field reversal, and both the Hall and longitudinal resistances display reproducible fluctuations. A comparison with measurements made on a Corbino disc reveals that these features occur due to conduction at the mesa edge. We propose a simple model based on edge states.

Published
2016

26. Electron-hole interactions and metal-insulator transitions in InAs/GaSb heterostructures

Author

Nicholas, R, Takashima, K, Kardynal, B, Petchsingh, C, Mason, N, Maude, D, Portal, J, and IPAP

Abstract

InAs/GaSb heterojunctions form bipolar 2-D layers due to the overlapping conduction and valence bands. Such systems have generated considerable interest recently due to the possibilities of gap formation by both excitonic and single particle interactions. The quantum Hall effect in this system shows a digital sequence oscillating from 0-1-0 conductance quanta and the diagonal resistivity, p. shows re-entrant insulating behaviour due to the formation of a total gap in the energy spectrum. The origin of the insulating behaviour is thought to be due to the formation of unusual counter propagating edge states where the electron and hole system interact to form closed loops which generate localised states. Cyclotron resonance on this system is found to show an increased effective mass when the electron and hole states approach each other physically and at high magnetic fields the resonances show large splittings which can be strongly temperature dependent.

Published
2016

28. Fabrication approaches for plasmon-improved photovoltaic cells

Author

Claudia Gritti, Radu Malureanu, Kardynal, B., and Andrei Lavrinenko

Abstract

During this talk we will present various fabrication approaches to improve the performance of photovoltaic (PV) cells by using metallic nanoparticles in order to generate photocurrent below the bandgap. This effect is possible due to the generation of surface plasmon polaritons (SPPs) in optimized nanoparticles.

Published
2013

30. Fabrication approaches for plasmon-improved photovoltaic cells

Author

Gritti, Claudia, Malureanu, Radu, Kardynal, B., Lavrinenko, Andrei, Gritti, Claudia, Malureanu, Radu, Kardynal, B., and Lavrinenko, Andrei

Abstract

During this talk we will present various fabrication approaches to improve the performance of photovoltaic (PV) cells by using metallic nanoparticles in order to generate photocurrent below the bandgap. This effect is possible due to the generation of surface plasmon polaritons (SPPs) in optimized nanoparticles.

Published
2013

31. Electron-hole interactions and metal-insulator transitions in InAs/GaSb heterostructures

Author

Nicholas, RJ, Takashima, K, Kardynal, B, Petchsingh, C, Mason, NJ, Maude, DK, and Portal, JC

Abstract

InAs/GaSb heterojunctions form bipolar 2-D layers due to the overlapping conduction and valence bands. Such systems have generated considerable interest recently due to the possibilities of gap formation by both excitonic and single particle interactions. The quantum Hall effect in this system shows a digital sequence oscillating from 0-1-0 conductance quanta and the diagonal resistivity, p. shows re-entrant insulating behaviour due to the formation of a total gap in the energy spectrum. The origin of the insulating behaviour is thought to be due to the formation of unusual counter propagating edge states where the electron and hole system interact to form closed loops which generate localised states. Cyclotron resonance on this system is found to show an increased effective mass when the electron and hole states approach each other physically and at high magnetic fields the resonances show large splittings which can be strongly temperature dependent.

Published
2001

33. Quantum dots for single photon and photon pair technology

Author

Ruggiero, B., Delsing, P., Granata, C., Pashkin, Y., Silvestrini, P., Stevenson, R. Mark, Young, Robert, Thompson, R. M., Yuan, Zhillang, Kardynal, B. E., Farrer, I., Ward, M. B., Ritchie, D. A., Shields, A. J., Ruggiero, B., Delsing, P., Granata, C., Pashkin, Y., Silvestrini, P., Stevenson, R. Mark, Young, Robert, Thompson, R. M., Yuan, Zhillang, Kardynal, B. E., Farrer, I., Ward, M. B., Ritchie, D. A., and Shields, A. J.

Abstract

The excitation of a quantum dot from its ground state depends on the probabilistic nature of carrier capture, and thus radiative decay can occur via a multi photon cascade. It is also possible that non-radiative initial exciton states can be formed when the spins of the component electron and heavy hole have the same sign. Time integrated and time resolved micro-photoluminescence experiments are presented that reveal the broader properties of single photon and multi-photon emission from InAs quantum dots, including single photon emission, polarisation correlated photon emission, and dark state blocking, and their implications in terms of quantum information technology are discussed.

Published
2006

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