Article
Chemistry, Physical
Benjamin A. Foutty, Jiachen Yu, Trithep Devakul, Carlos R. Kometter, Yang Zhang, Kenji Watanabe, Takashi Taniguchi, Liang Fu, Benjamin E. Feldman
Summary: By studying twisted double-bilayer WSe2, we have identified charge-ordered phases at multiple integer and fractional moire fillings. Through experiments with magnetic fields and displacement fields, we have observed spin-polarized ground states and a metal-insulator transition. These results demonstrate the control over spin and valley character in this system.
Article
Multidisciplinary Sciences
L. Banszerus, S. Moeller, C. Steiner, E. Icking, S. Trellenkamp, F. Lentz, K. Watanabe, T. Taniguchi, C. Volk, C. Stampfer
Summary: Understanding the coupling of electron spin with orbital degrees of freedom is crucial for applications in spin-based electronics and quantum computation. Recent experiments in bilayer graphene quantum dots have demonstrated the observation of spin-valley coupling and the effect of Kane-Mele type spin-orbit coupling in lifting the degeneracy of spin and valley states. These findings provide important insights for potential advancements in spin and spin-valley qubit operations.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Applied
Priyabrata Mudi, Shailesh K. Khamari, T. K. Sharma
Summary: Numerical simulations were conducted to investigate the factors affecting the inverse spin Hall voltage (V-ISHE) in n-GaAs opto-spintronic devices, revealing that the magnitude of V-ISHE can be significantly enhanced by an external electric field, with the curve shape dependent on excitation energy. Different behaviors of V-ISHE were observed depending on the valley into which carriers were injected, with a dual slope behavior seen for carriers injected into the L-valley of GaAs. A peak-like behavior of V-ISHE with dopant density was predicted consistently.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Konstantinos Prousalis, Agis A. Iliadis, Evangelos K. Evangelou, Nikos Konofaos
Summary: This study reports on the behavior of charge noise and spin noise for a fundamental logic unit of four qubit embedded in an AlAs/GaAs heterostructure using modeling and simulation at the atomic level. The approach presented here can serve as the basis for expanding to larger logical blocks of qubits in advanced simulations.
Article
Quantum Science & Technology
Guanjie He, Guo Xuan Chan, Xin Wang
Summary: Recent studies show that a multi-electron double-quantum-dot system may have advantages over the traditional case with only two confined electrons. The electron-phonon dephasing in a GaAs multi-electron double-quantum-dot system is investigated in both biased and unbiased cases. The results reveal that, in the biased case, the electron-phonon dephasing rate does not increase with the number of electrons, and a merit figure based on the exchange energy and dephasing rate actually increases with the number of electrons in the experimentally relevant range.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Multidisciplinary Sciences
Cedric Robert, Sangjun Park, Fabian Cadiz, Laurent Lombez, Lei Ren, Hans Tornatzky, Alistair Rowe, Daniel Paget, Fausto Sirotti, Min Yang, Dinh Van Tuan, Takashi Taniguchi, Bernhard Urbaszek, Kenji Watanabe, Thierry Amand, Hanan Dery, Xavier Marie
Summary: The study demonstrates efficient spin/valley optical pumping of resident electrons in n-doped WSe2 and WS2 monolayers, achieving large dynamic polarization of resident electrons using circular light with continuous wave laser and appropriate doping and excitation densities.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Shengnan Xu, Chen Si, Yang Li, Bing-Lin Gu, Wenhui Duan
Summary: The study reveals the existence of a satellite Gamma valley in monolayer MoS2, providing an additional relaxation path for holes and ensuring ultrafast valley depolarization. It may have significant implications for controlling valley depolarization in multivalley materials.
Article
Optics
Lifu Zhang, Jie Jiang, Christian Multunas, Chen Ming, Zhizhong Chen, Yang Hu, Zonghuan Lu, Saloni Pendse, Ru Jia, Mani Chandra, Yi-Yang Sun, Toh-Ming Lu, Yuan Ping, Ravishankar Sundararaman, Jian Shi
Summary: Researchers demonstrate a persistent spin helix in an organic-inorganic hybrid ferroelectric halide perovskite. They show that the spin-polarized band structure can be switched via an intrinsic ferroelectric field. This discovery has the potential to resolve the control-relaxation dilemma in spintronic devices.
Article
Quantum Science & Technology
Peihao Huang, Xuedong Hu
Summary: The electron spin qubit in silicon quantum dots shows promise for quantum information processing due to scalability and long coherence. Recent progress utilizing micromagnets to generate synthetic spin-orbit coupling has enabled high-fidelity spin manipulation and strong interaction with cavity photons. Despite technical challenges, enhancing electrical manipulation and controlling spin dephasing through spin-valley mixing can lead to high-quality spin qubits.
NPJ QUANTUM INFORMATION
(2021)
Article
Physics, Applied
Bo Wang, Gaoshuai Wei, Jianing Chen, Li Wang
Summary: This study investigates ultrafast spin polarization in semi-insulating GaAs using terahertz time-domain spectroscopy. The results demonstrate that the transmitted and reflected terahertz signals exhibit different dynamic evolutions under the excitation of different polarization laser pulses, indicating the generation and relaxation process of spin-polarized electrons.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Caspar Hopfmann, Nand Lal Sharma, Weijie Nie, Robert Keil, Fei Ding, Oliver G. Schmidt
Summary: The study on heralded spin preparation using excited state resonances of GaAs quantum dots revealed properties of different quantum dot energy levels, simplified determination of spin preparation fidelities, and found high spin preparation fidelities and short decay times.
Article
Physics, Multidisciplinary
Chuyao Tong, Annika Kurzmann, Rebekka Garreis, Wei Wister Huang, Samuel Jele, Marius Eich, Lev Ginzburg, Christopher Mittag, Kenji Watanabe, Takashi Taniguchi, Klaus Ensslin, Thomas Ihn
Summary: The study reports experiments on coupled bilayer graphene double quantum dots, where the spin and valley states are precisely controlled, enabling the observation of two-electron combined blockade physics. The switching of selection rules is demonstrated by switching between different ground states with gate and magnetic-field tuning, showing either valley blockade or spin blockade depending on the ground state configuration.
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Spencer Batalden, Vanessa Sih
Summary: Time-resolved Kerr rotation microscopy was used to generate and measure spin valley polarization in monolayer tungsten diselenide grown by MOCVD. The Kerr signal showed bi-exponential decay with time constants of 100 ps and 3 ns, revealing larger spin valley polarization near the edges of triangular flakes. Spatial dependence of the Kerr signal was observed across multiple WSe2 flakes, indicating it is not due to spin diffusion on the nanosecond timescale.
Article
Materials Science, Multidisciplinary
Shuo Li, Junjie He, Lukas Grajciar, Petr Nachtigall
Summary: Surface engineering can induce valley polarization in 2D MXenes, breaking their inversion symmetry and providing a new design opportunity. This study also demonstrates the potential for diverse magnetic orders and properties in MXenes with surface engineering.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Materials Science, Multidisciplinary
Vasily Kravtsov, Aleksey D. Liubomirov, Roman Cherbunin, Alessandro Catanzaro, Armando Genco, Daniel Gillard, Evgeny M. Alexeev, Tatiana Ivanova, Ekaterina Khestanova, Ivan A. Shelykh, Alexander Tartakovskii, Maurice S. Skolnick, Dmitry N. Krizhanovskii, Ivan Iorsh
Summary: Research shows that stable valley polarization can be achieved by adjusting the spin-valley relaxation dynamics in heterobilayers with different structures and optical properties. Through experimental and theoretical analysis, the contributions of interlayer exciton recombination and charge carrier spin depolarization to valley dynamics are uncovered.
Article
Nanoscience & Nanotechnology
Nadine Leisgang, Shivangi Shree, Ioannis Paradisanos, Lukas Sponfeldner, Cedric Robert, Delphine Lagarde, Andrea Balocchi, Kenji Watanabe, Takashi Taniguchi, Xavier Marie, Richard J. Warburton, Iann C. Gerber, Bernhard Urbaszek
NATURE NANOTECHNOLOGY
(2020)
Article
Physics, Applied
Eric Vetter, Melike Biliroglu, Dovletgeldi Seyitliyev, Pramod Reddy, Ronny Kirste, Zlatko Sitar, Ramon Collazo, Kenan Gundogdu, Dali Sun
APPLIED PHYSICS LETTERS
(2020)
Article
Chemistry, Physical
Juliana Barros Barbosa, Pierre Louis Taberna, Valerie Bourdon, Iann C. Gerber, Romuald Poteau, Andrea Balocchi, Xavier Marie, Jerome Esvan, Pascal Puech, Antoine Barnabe, Lucianna Da Gama Fernandes Vieira, Ionut-Tudor Moraru, Jean Yves Chane-Ching
APPLIED CATALYSIS B-ENVIRONMENTAL
(2020)
Article
Multidisciplinary Sciences
Ioannis Paradisanos, Gang Wang, Evgeny M. Alexeev, Alisson R. Cadore, Xavier Marie, Andrea C. Ferrari, Mikhail M. Glazov, Bernhard Urbaszek
Summary: The study measured the first stages of carrier-phonon interaction in monolayer WSe2, revealing periodic maxima in hot photoluminescence intensity attributed to phonon cascades. The intermediate states in the conduction band at the Lambda-valley of the Brillouin zone are found to participate in the cascade process of tungsten diselenide monolayers.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Applied
Elisa Vitiello, Simone Rossi, Christopher A. Broderick, Giorgio Gravina, Andrea Balocchi, Xavier Marie, Eoin P. O'Reilly, Maksym Myronov, Fabio Pezzoli
PHYSICAL REVIEW APPLIED
(2020)
Article
Chemistry, Multidisciplinary
Rajagopal Shyamala Joshya, Helene Carrere, Victor Guadalupe Ibarra-Sierra, Juan Carlos Sandoval-Santana, Vladimir K. Kalevich, Eugeniyus L. Ivchenko, Xavier Marie, Thierry Amand, Alejandro Kunold, Andrea Balocchi
Summary: By introducing a new method, conventional dilute nitride GaAs-based semiconductor epilayers have been given a chiral photoconductivity for the detection of light helicity. The light polarization state and intensity can be determined by a simple conductivity measurement, as the conduction electron spin polarization is linked to the excitation light polarization. This approach eliminates the need for optical elements in front of a non-chiral detector, allowing for easier integration and miniaturization.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Physics, Multidisciplinary
Meryem Benelajla, Elena Kammann, Bernhard Urbaszek, Khaled Karrai
Summary: Confocal microscopy is crucial for imaging in biological and physical sciences. Resonant fluorescence experiments are conducted under challenging cross-polarization conditions. Using reflective surfaces and a confocal arrangement, a high cross-polarization extinction ratio of over 108 is achieved, providing practical implications for various experiments.
Article
Chemistry, Physical
Andre Philipp Frauendorf, Andre Niebur, Lena Harms, Shivangi Shree, Bernhard Urbaszek, Michael Oestreich, Jens Huebner, Jannika Lauth
Summary: Wet-chemical synthesis methods have been shown to be promising for the straightforward solution-processing of quasi two-dimensional transition metal dichalcogenides (TMDs), with their photoluminescence properties virtually unexplored. This study demonstrates room temperature micro-PL of delicate ultrathin colloidal WS2 nanosheets synthesized from WCl6 and elemental sulfur, revealing comparable characteristics to exfoliated TMD monolayers and promising long-term air stability. These results suggest colloidal TMDs as easily synthesized and highly promising 2D semiconductors with optical properties fully competitive with conventionally fabricated ultrathin TMDs.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Physics, Applied
V. G. Ibarra-Sierra, J. C. Sandoval-Santana, R. S. Joshya, H. Carrere, L. A. Bakaleinikov, V. K. Kalevich, E. L. Ivchenko, X. Marie, T. Amand, A. Balocchi, A. Kunold
Summary: The optoelectronic compact circular polarimeter proposed in this study utilizes GaAs1-xNx as the base material and measures circular polarization degree and light intensity through spin-dependent capture and hyperfine interaction. Without bulky movable parts, it is easy to integrate and distinguish the handedness of incident light.
PHYSICAL REVIEW APPLIED
(2021)
Article
Optics
A. Aguirre-Perez, R. S. Joshya, H. Carrere, X. Marie, T. Amand, A. Balocchi, A. Kunold
Summary: We demonstrate the application of a two stage machine learning algorithm to correlate the electrical signals from a GaAsxN1-x circular polarimeter with the properties of an incident light beam. The algorithm accurately predicts the intensity, degree of circular polarization (DCP), and handedness of the light beam, and can be easily adjusted to other device configurations.
Article
Multidisciplinary Sciences
Ryan J. Gelly, Dylan Renaud, Xing Liao, Benjamin Pingault, Stefan Bogdanovic, Giovanni Scuri, Kenji Watanabe, Takashi Taniguchi, Bernhard Urbaszek, Hongkun Park, Marko Loncar
Summary: In this study, a tapered optical fibre is used to generate strain and observe the participation of dark excitons in high-strain regions. The near-field optical response of WSe2 monolayers is probed to reveal the dynamics of free excitons at cryogenic temperatures.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Lukas Sponfeldner, Nadine Leisgang, Shivangi Shree, Ioannis Paradisanos, Kenji Watanabe, Takashi Taniguchi, Cedric Robert, Delphine Lagarde, Andrea Balocchi, Xavier Marie, Iann C. Gerber, Bernhard Urbaszek, Richard J. Warburton
Summary: The coupling of intralayer A and B excitons and interlayer excitons (IE) in a two-dimensional semiconductor, homobilayer MoS2, is studied. The optical susceptibility measurements reveal both the magnitude and phase of the coupling constants. The coupling mechanisms between IE-B and IE-A are interpreted as hole tunneling and electron-hole exchange, respectively. It is also found that even in a monolayer, the A and B excitons have mixed spin states. Moreover, a bright and highly tunable lowest-energy momentum-direct exciton is achieved under high electric fields.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
D. Beret, L. Ren, C. Robert, L. Foussat, P. Renucci, D. Lagarde, A. Balocchi, T. Amand, B. Urbaszek, K. Watanabe, T. Taniguchi, X. Marie, L. Lombez
Summary: We investigated the diffusion process of negatively charged excitons in a WSe2 monolayer and found nonlinear diffusion behavior. The dynamics of different excitonic species were examined, and a bimolecular formation mechanism was proposed. Based on our experimental observations, a phenomenological model suggesting the coexistence of two populations, with different diffusion mechanisms, was proposed.
Article
Materials Science, Multidisciplinary
Ioannis Paradisanos, Andres Manuel Saiz Raven, Thierry Amand, Cedric Robert, Pierre Renucci, Kenji Watanabe, Takashi Taniguchi, Iann C. Gerber, Xavier Marie, Bernhard Urbaszek
Summary: In this study, polarization-resolved second harmonic generation spectroscopy was used to investigate the influence of the twist angle on the SHG signal of MoS2/WSe2 heterostructures. The experimental results show that in heterostructures with close to zero twist angle, changes in exciton resonance energies and the appearance of new resonances in linear and nonlinear susceptibilities were observed.
Review
Physics, Applied
Shivangi Shree, Ioannis Paradisanos, Xavier Marie, Cedric Robert, Bernhard Urbaszek
Summary: Potential applications in photonics and optoelectronics rely on understanding light-matter interactions on an atomic monolayer scale. Thin 2D transition metal dichalcogenides, like MoS2 and WSe2, are model systems for layered semiconductors with a visible optical spectrum bandgap. Optical spectroscopy is a powerful tool to access electronic band structure and crystal quality details, with the ability to tune absorption and emission features. Practical set-ups and the influence of sample environment on emission and absorption mechanisms are crucial factors.
NATURE REVIEWS PHYSICS
(2021)
