Article
Physics, Condensed Matter
Samir Melkoud, Abdelhakim Nafidi, Driss Barkissy
Summary: In this study, we theoretically investigate the electronic band-structures and quantum magneto-transport properties of GaAs/Al0.18Ga0.82As multi-quantum wells at low temperature. The effect of well and barrier thicknesses on the band structure and bandgap is studied. The results are important for the design and engineering of multiple quantum wells infrared detectors.
MICRO AND NANOSTRUCTURES
(2022)
Article
Chemistry, Multidisciplinary
Michael Berger, Dominik Schulz, Jamal Berakdar
Summary: Quantum scars refer to enhanced localization of probability density of states in spectral regions with high energy levels. The study showed that spin-dependent scarring occurs in spin-coupled electronic systems, which can be detected through transport measurements or spin-polarized scanning tunneling spectroscopy.
Article
Physics, Multidisciplinary
M. Solaimani, M. Izadifard
Summary: The study investigated the spin polarization efficiency and spin-dependent transmission of electrons passing through a multiple quantum well structure made of GaAs/Al0.3Ga0.7As. The number of wells in a constant total length was presented as a tuning tool for spin filtering purposes, with 100% spin polarization and spin-dependent transmission observed in some energy intervals.
INDIAN JOURNAL OF PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Slawomir P. Lepkowski
Summary: In this study, the quantum spin Hall effect in InN/InGaN coupled multiple quantum wells is theoretically studied. It is found that a topological insulator can be achieved in triple quantum wells when the In content in the interwell barriers is greater than or equal to the In content in the external barriers. In quadruple quantum wells, a topological insulator phase can only be achieved when the In content in the interwell barriers is larger than in the external barriers.
Article
Optics
A. L. Subasi, M. Iskin
Summary: We employed the Bogoliubov approximation to investigate the influence of quantum geometry on the superfluid properties of spin-orbit-coupled Bose gas. The study derived the low-energy Bogoliubov spectrum for a plane-wave condensate in the lower helicity band and found that the geometric contributions to the sound velocity exhibit distinct linear dependencies on the interaction strength, in contrast to the conventional contribution. The research also examined the roton instability of the condensate and determined the phase-transition boundary, as well as derived the superfluid density tensor by introducing a phase twist on the condensate order parameter and studying the relative importance of its contribution from interband processes related to quantum geometry.
Article
Physics, Applied
W. Wang, Q. X. Wang, J. Y. Fu
Summary: This study shows that by adjusting the inner band offset in stepped quantum wells, it is possible to control spin-orbit coupling and selectively suppress spin relaxation. The researchers also discuss the effects of wave function overlap and parity on interband spin-orbit coupling.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Physics, Condensed Matter
Fanhua Meng, Jianhua Zhao, Jie Cheng, Wen Liu
Summary: This study investigates the spin-orbit coupling (SOC) in n-quantum-well structures with occupied n subbands using an external gate potential. It is found that the SOC coefficient of the lowest subband is always much larger than those of the other subbands in triple to septuple quantum-well structures, leading to greater spin splitting and desirable spin polarization. The SOC can be selectively controlled by adjusting the gate, although it becomes less gate-dependent when more local wells are incorporated in the case of n-subband occupation. These findings are attributed to charge transfer among the subwells and the variation gradient of the potential energy along the growth direction of the quantum wells.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Physics, Condensed Matter
H. S. Aydinoglu, M. Sayrac, M. E. Mora-Ramos, F. Ungan
Summary: We have conducted a theoretical simulation to investigate the influence of applied external electric and magnetic fields, as well as changes in structure parameters, on the optical properties of GaAs/GaAlAs asymmetric double graded quantum wells (ADGQWs).
SOLID STATE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Yonatan Ashlea Alava, Daisy Q. Wang, Chong Chen, David A. Ritchie, Arne Ludwig, Julian Ritzmann, Andreas D. Wieck, Oleh Klochan, Alexander R. Hamilton
Summary: The use of in situ epitaxial aluminum gates in GaAs/AlxGa1-xAs heterostructures effectively eliminates surface charge scattering, improving electron mobility. The electron mobility is strongly influenced by the thickness of aluminum, and the type of semiconductor wetting layer used at the semiconductor-aluminum interface. For 8 nm thick aluminum, the choice of wetting layer also impacts electron mobility, with aluminum on GaAs resulting in higher mobility compared to other wetting layers.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Ariel Khakshoor, Jeremy Belhassen, Michael Bendayan, Avi Karsenty
Summary: GaAs/GaAlAs/GaAs Asymmetric Quantum Wells (AQW) have multiple advantages in the domain of inter-sub-band transition (ISBT) and serve as the basic structures for advanced electro-optical devices. A new approach enables the creation and control of Self-Induced Electrical Fields (SIEF) by varying the dopant concentration in the structure.
RESULTS IN PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Qingbo Wang, Wenjing Zhao, Linghua Wen
Summary: The study reveals that spin-orbit coupling has a significant influence on the dynamics of kicked pseudo-spin-1/2 Bose-Einstein condensates under different conditions, mainly reflected in the different behaviors of density distribution and energy evolution.
RESULTS IN PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Zhi-Hai Zhang, Jian-Hui Yuan
Summary: In this paper, we investigate the influence of applied electric field on the energy levels and optical properties of a Gaussian confinement quantum dot. By utilizing the compact density matrix and iterative approach, we calculate the second harmonic generation (SHG), linear and nonlinear optical absorption coefficients. Considering all possible transition routes in the one electron approximation, we find that the energy levels and nonlinear optical properties of the quantum dot are significantly affected by the applied electric field, with distinct contributions from different transition routes. Our results highlight the importance of geometric parameters and applied electric field in understanding the electronic and optical properties of quantum dots, which could have implications in related research fields.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2023)
Article
Optics
Lijun Yang
Summary: Our study demonstrates the importance of quantum fluctuations in understanding the superfluid properties of spin-orbit-coupled Bose-Einstein condensates.
Article
Nuclear Science & Technology
Zhi-Fu Zhu, Ji-Jun Zou, Zhi-Jia Sun, He Huang, Qing-Lei Xiu, Zhong-Ming Zhang, Yong Gan, Chen-Xian Guo, Shao-Tang Wang, Xiu-Ping Yue, Guo-Li Kong
Summary: In this study, p-i-n AlxGa1-xAs/GaAs detectors with graded compositions and graded doping were grown and prepared. The devices exhibited good p-n junction diode characteristics and high electric field strength under an unbiased voltage. The detectors showed small full width at half maximum and high charge collection efficiency, making them the most advanced and promising unbiased detectors reported to date.
NUCLEAR SCIENCE AND TECHNIQUES
(2022)
Article
Chemistry, Physical
Nebile Isik Goktas, Vladimir G. Dubrovskii, Ray R. LaPierre
Summary: By adjusting the growth conditions of the InGaAs shell, different structural and morphological GaAs-InGaAs-GaAs core-shell-shell nanowire structures can be obtained. Increasing the In concentration in the InGaAs shell transitions the growth mode from preferential deposition at the NW base to the Stranski-Krastanov growth mode where InGaAs islands form along the NW length. Controlling the shell growth conditions can affect the optical properties and photoluminescence emission.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Maximilian Otteneder, Stefan Hubmann, Xiaobo Lu, Dmitry A. Kozlov, Leonid E. Golub, Kenji Watanabe, Takashi Taniguchi, Dmitri K. Efetov, Sergey D. Ganichev
Article
Multidisciplinary Sciences
Shivangi Shree, Delphine Lagarde, Laurent Lombez, Cedric Robert, Andrea Balocchi, Kenji Watanabe, Takashi Taniguchi, Xavier Marie, Iann C. Gerber, Mikhail M. Glazov, Leonid E. Golub, Bernhard Urbaszek, Ioannis Paradisanos
Summary: Efficient second-harmonic generation (SHG) occurs for crystals with broken inversion symmetry, such as transition metal dichalcogenide monolayers. Here the authors show SHG tuning in bilayer MoS2 - an inversion-symmetric crystal - mediated by interlayer excitons.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Applied
S. N. Danilov, L. E. Golub, T. Mayer, A. Beer, S. Binder, E. Monch, J. Minar, M. Kronseder, C. H. Back, D. Bougeard, S. D. Ganichev
Summary: The study reports a complex nonlinear intensity dependence of photogalvanic currents induced by infrared radiation in three-dimensional topological insulators, showing a superlinear rise followed by saturation. The observed nonlinearities provide information about the Fermi-level position and energy relaxation times of Dirac fermions in topological surface states.
PHYSICAL REVIEW APPLIED
(2021)
Article
Materials Science, Multidisciplinary
M. Hild, L. E. Golub, A. Fuhrmann, M. Otteneder, M. Kronseder, M. Matsubara, T. Kobayashi, D. Oshima, A. Honda, T. Kato, J. Wunderlich, C. Back, S. D. Ganichev
Summary: We report on spin ratchet currents driven by terahertz radiation electric fields in a Co/Pt magnetic metamaterial formed by triangle-shaped holes. The radiation causes a polarization-independent spin-polarized ratchet current by inducing periodic asymmetric radiation intensity distribution and a phase-shifted periodic asymmetric electrostatic force. The magnetization of the Co/Pt film results in a spin ratchet current caused by both the anomalous Hall and the anomalous Nernst effects, as well as a polarization-dependent trigonal spin photocurrent.
Article
Materials Science, Multidisciplinary
N. V. Leppenen, L. E. Golub
Summary: The theory of the linear photogalvanic effect in three-dimensional topological insulators is discussed. Both the shift contribution caused by coordinate shifts and the ballistic contribution caused by optical absorption and scattering have the same magnitude. The ballistic contribution dominates in the nonlinear regime due to saturation of direct optical transitions. This distinction is important for experiments.
Article
Materials Science, Multidisciplinary
E. Monch, S. O. Potashin, K. Lindner, I. Yahniuk, L. E. Golub, V. Yu. Kachorovskii, V. V. Bel'kov, R. Huber, K. Watanabe, T. Taniguchi, J. Eroms, D. Weiss, S. D. Ganichev
Summary: We present a study on the conversion of terahertz radiation into a dc current in spatially modulated bilayer graphene, tunable by magnetic field and gate voltage. We observe a sharp cyclotron resonance in the photocurrent and discover two effects caused by electron-electron interaction: the splitting of the resonance due to Coulomb coupling and the suppression of its second harmonic due to interparticle collisions. A theoretical model that fits the experimental data perfectly is developed, suggesting that the ratchet current is generated in the hydrodynamic regime of nonideal electron liquid.
Article
Materials Science, Multidisciplinary
L. E. Golub, M. M. Glazov
Summary: We theoretically demonstrate that electromagnetic waves propagating in the transparency region of a noncentrosymmetric medium can generate a direct current. The Raman scattering of light by free carriers in the system is responsible for this effect.
Article
Materials Science, Multidisciplinary
M. M. Glazov, L. E. Golub
Summary: We develop a theory for the spin and valley Hall effects in two-dimensional systems caused by asymmetricskew-scattering. The results show that the scattering asymmetry only appears in processes where interaction between particles in the initial and intermediate states is present. For degenerate electrons or nondegenerate particles, the spin and valley currents induced by interparticle collisions are suppressed, and their steady-state values are proportional to the squared temperature or density, respectively. The study also demonstrates strong deviations from the conventional picture of interparticle scattering for the skew scattering of two-dimensional degenerate bosons, such as excitons or exciton polaritons.
Article
Physics, Multidisciplinary
M. O. Nestoklon, L. E. Golub
Summary: The theory of weak localization is developed for two-dimensional holes in the presence of an in-plane magnetic field. The study shows that the Zeeman splitting in the hole momentum leads to spin-dependent phase changes that affect quantum interference. The negative correction to conductivity is found to decrease by half due to the in-plane magnetic field. Furthermore, the positive magnetoconductivity caused by weak localization in a classically weak perpendicular field is calculated for both quadratic and quartic Zeeman hole splittings, and the conductivity corrections in these cases are found to be very similar.
JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
V. N. Leppenen, L. E. Golub
Summary: A theory of optical absorption in topological insulators is developed for nonlinear light intensity regime, focusing on the behavior of linearly and circularly polarized light in surface and edge states. The study considers the elastic scattering of photocarriers and shows that it strongly suppresses absorption bleaching at high intensity. The presence of elastic scattering also affects the linear-circular dichroism and photocurrents generated in the edge states. These effects can be observed in the terahertz frequency range at modern laser intensities.
Article
Materials Science, Multidisciplinary
E. Moench, S. O. Potashin, K. Lindner, I Yahniuk, L. E. Golub, V. Yu Kachorovskii, V. V. Bel'kov, R. Huber, K. Watanabe, T. Taniguchi, J. Eroms, D. Weiss, S. D. Ganichev
Summary: We report the observation of ratchet effect in bilayer graphene, where direct electric current is generated in response to external terahertz radiation due to the broken inversion symmetry caused by an asymmetric dual-grating gate potential. The ratchet current shows different frequency dependencies at high and low temperatures, decreasing as proportional to 1/omega 2 and 1/omega 6, respectively. The theory predicts that the frequency dependence of the ratchet current is sensitive to the ratio of electron-impurity and electron-electron scattering rates.
Article
Materials Science, Multidisciplinary
Alexander N. Poddubny, Leonid E. Golub
Summary: This theoretical study explores the spatial distribution of polarizations in an array of resonant electromagnetic dipole emitters coupled to a one-dimensional waveguide. The ratchet effect, resulting in spatial asymmetry of emitter occupations under symmetrical pumping, is driven by periodic modulation of emitter resonance frequencies. The research identifies optimal conditions for maximal asymmetry and demonstrates that the ratchet effect can be enhanced by the formation of topological electromagnetic edge states enabled by frequency modulation.
Article
Materials Science, Multidisciplinary
A. Trifonov, I. A. Akimov, L. E. Golub, E. L. Ivchenko, I. A. Yugova, A. N. Kosarev, S. E. Scholz, C. Sgroi, A. Ludwig, A. D. Wieck, D. R. Yakovlev, M. Bayer
Summary: The presence of a large in-plane heavy-hole g factor in symmetric self-assembled (001) (In,Ga)As/GaAs quantum dots is revealed due to the warping of valence-band states. This warping dominates over the established mechanism associated with reduced symmetry and mixing of heavy-hole and light-hole states in the quantum dots. The effect of band warping is demonstrated in the unique angular dependence of the trion photon echo signal on the direction of the external magnetic field, resulting in a uniform magnetic-field-induced optical anisotropy for the entire quantum dot ensemble.
Article
Materials Science, Multidisciplinary
S. Candussio, L. E. Golub, S. Bernreuter, T. Joetten, T. Rockinger, K. Watanabe, T. Taniguchi, J. Eroms, D. Weiss, S. D. Ganichev
Summary: This study reports the observation of terahertz-radiation-induced edge photogalvanic currents in graphene, which exhibit nonlinearity in intensity and are controlled by various factors. The nonlinearity is attributed to the interplay of direct interband optical transitions and Drude-like absorption mechanisms. Both photocurrents saturate at high intensities but demonstrate different intensity dependencies, while the total photocurrent shows a complex sign-alternating intensity dependence. The experimental data and theory developed show good agreement regarding the functional behavior of the saturation intensities and amplitudes of the photogalvanic currents under different conditions.
Article
Materials Science, Multidisciplinary
N. Leppenen, L. E. Golub, E. L. Ivchenko
Summary: In this study, the interaction between photocarriers in two-dimensional Dirac materials was considered, revealing enhanced absorbance, particularly in the narrow interband edge region. An approximation of weak interaction was developed to reproduce the main features of the exactly calculated Sommerfeld factor. A substantial reduction of this factor at higher frequencies was shown due to single-particle energy renormalization.
