Article
Chemistry, Multidisciplinary
Lunjie Zeng, Jonatan Holmer, Rohan Dhall, Christoph Gammer, Andrew M. Minor, Eva Olsson
Summary: Strain engineering is shown to be an effective method for tailoring the electronic and optoelectronic properties of semiconductor nanomaterials and nanodevices, leading to novel functionalities. Experimental evidence demonstrates that the conductivity and hole mobility of gallium arsenide nanowires vary with different levels of uniaxial tensile stress, attributed to changes in valence band structure caused by stress and strain. Furthermore, lattice strain in the nanowires is quantified and a significant red shift of the band gap induced by stress and strain is observed.
Article
Materials Science, Multidisciplinary
Yi Huang, B. I. Shklovskii, M. A. Zudov
Summary: Motivated by recent breakthroughs in molecular beam epitaxy of GaAs/AlGaAs quantum wells, this study examines the contributions to mobility and quantum mobility from various scattering mechanisms and their dependencies on the electron density. It is found that at lower electron densities, transport and quantum mobility are limited by unintentional background impurities and follow a power-law dependence. The consideration of other scattering mechanisms suggests that interface roughness is likely a limiting factor for transport and quantum mobility at higher electron densities. Future measurements of quantum mobility should provide information about the distribution of background impurities in GaAs and AlGaAs.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Naotaka Kasuya, Junto Tsurumi, Toshihiro Okamoto, Shun Watanabe, Jun Takeya
Summary: By utilizing an ion gel on top of a solution-processed, single-crystalline organic semiconductor film, researchers have observed a two-dimensional hole gas with high carrier density. The findings demonstrate the potential for tailoring low-dimensional electronic states through molecularly engineered heterointerfaces.
Article
Physics, Multidisciplinary
Adbhut Gupta, J. J. Heremans, Gitansh Kataria, Mani Chandra, S. Fallahi, G. C. Gardner, M. J. Manfra
Summary: Through experiments and simulations, we found collective transport phenomena in both hydrodynamic and ballistic transport regimes in a high-mobility GaAs/AlGaAs heterostructure, showing that negative nonlocal resistances and current vortices are not exclusive to the hydrodynamic regime. The importance of device design, measurement schemes, and one-to-one modeling of experimental devices is highlighted in distinguishing various transport regimes.
PHYSICAL REVIEW LETTERS
(2021)
Article
Engineering, Electrical & Electronic
M. Villarreal-Faz, P. G. Meza-Reyes, A. Belio-Manzano, L. M. Hernandez-Gaytan, C. A. Mercado-Ornelas, F. E. Perea-Parrales, J. P. Olvera-Enriquez, L. I. Espinosa-Vega, A. G. Rodriguez, C. M. Yee-Rendon, V. H. Mendez-Garcia, I. E. Cortes-Mestizo
Summary: This study presents the optical non-destructive characterization of tin-doped GaNxAs1-x layer grown on GaAs (100). GaNAs:Sn samples were grown using molecular beam epitaxy with nitrogen molar content at two different values, x similar to 0.001 and similar to 0.02. The n-type doping concentration was controlled by the Sn effusion cell temperature (T-Sn) ranging from 700 to 850 degrees C. Different characterization techniques were used to evaluate the crystallinity, vibrational modes, donor atom concentration, E-broadening parameter, and electrical properties of the samples. Results showed that the samples with x similar to 0.02 exhibited enhanced properties related to tin incorporation for each characterization technique.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2023)
Article
Physics, Multidisciplinary
Sangita R. Panda, Manoranjan Pradhan, Trinath Sahu, Ajit Kumar Panda
Summary: This study investigates the effect of asymmetric doping concentrations on the electron mobility in GaAs/InGaAs-based single and double quantum well pseudomorphic high electron mobility transistor structures. The results show that different doping concentrations lead to asymmetric distributions of subband wave functions, which in turn influence the subband mobility. It is found that increasing the doping concentration of one layer in a single quantum well structure enhances the mobility nonlinearly. In double quantum well structures, the distribution of subband wave functions changes depending on the relative doping concentrations, resulting in a nonlinear variation of the mobility.
Article
Materials Science, Multidisciplinary
Yoon Jang Chung, A. Gupta, K. W. Baldwin, K. W. West, M. Shayegan, L. N. Pfeiffer
Summary: Ultrahigh-mobility GaAs two-dimensional electron systems (2DESs) have been a significant platform for condensed-matter physics research for several decades. Continuous improvement in sample quality has enabled scattering-free transport and led to the emergence of exotic many-body phenomena. Recent research shows the potential for further increasing the mobility limit of GaAs 2DESs, and discusses scenarios for achieving mobility values exceeding 100 x 10(6) cm(2)/Vs.
Article
Crystallography
Cui Yu, Chuangjie Zhou, Jianchao Guo, Zezhao He, Mengyu Ma, Hongxing Wang, Aimin Bu, Zhihong Feng
Summary: This study investigates the carrier scattering mechanisms of a two-dimensional hole gas in a hydrogen-terminated diamond and identifies surface roughness scattering and ionic impurity scattering as the dominant sources of scattering. It is also found that impurity scattering is enhanced after a high-temperature Al2O3 deposition process.
Review
Chemistry, Multidisciplinary
Hanyin Zhang, Yubo Geng, Jin Huang, Zixiao Wang, Kun Du, Haoyuan Li
Summary: The development of smartphones and electric cars requires higher capacity, faster charging, and safer electrochemical energy storage devices. Two-dimensional covalent organic frameworks (2D COFs) have received increasing attention as potential electrode and electrolyte materials in energy storage devices. The nanoscale porous structure and tunable functionalities of 2D COFs offer new possibilities for electrochemical energy storage materials. Understanding the charge and mass transport mechanisms of 2D COFs is essential for their development in energy storage devices. This review provides an overview of recent studies and fundamental elements of charge and mass transport in 2D COFs, as well as discussing the paths for their use in energy storage devices.
ENERGY & ENVIRONMENTAL SCIENCE
(2023)
Article
Physics, Multidisciplinary
T. Pohl, Y. L. Sun, A. Obertelli, J. Lee, M. Gomez-Ramos, K. Ogata, K. Yoshida, B. S. Cai, C. X. Yuan, B. A. Brown, H. Baba, D. Beaumel, A. Corsi, J. Gibelin, A. Gillibert, K. I. Hahn, T. Isobe, Y. Kondo, T. Kobayashi, Y. Kubota, P. Li, P. Liang, H. N. Liu, J. Liu, T. Lokotko, F. M. Marques, Y. Matsuda, T. Motobayashi, T. Nakamura, N. A. Orr, H. Otsu, V. Panin, S. Y. Park, S. Sakaguchi, M. Sasano, H. Sato, H. Sakurai, Y. Shimizu, A. I. Stefanescu, L. Stuhl, D. Suzuki, T. Uesaka, H. Wang, X. Xu, Z. H. Yang, K. Yoneda, J. Zenihiro
Summary: We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient 14O nucleus with large Fermi-surface asymmetry Sn - Sp 1/4 18.6 MeV at similar to 100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the 13N and 13O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer are important tools for investigating single-particle strengths and correlations in atomic nuclei.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
You Kyoung Chung, Junho Lee, Weon-Gyu Lee, Dongchul Sung, Sudong Chae, Seungbae Oh, Kyung Hwan Choi, Bum Jun Kim, Jae-Young Choi, Joonsuk Huh
Summary: Nb2Se9, a novel material, shows promise for nanoscale electronic devices due to its suitable band gap, high carrier mobility, and chemical stability. With a noticeable band gap and high electron mobility compared to other 2D materials, Nb2Se9 demonstrates potential for use in nanoscale electronics and mid-infrared photodetectors.
Article
Materials Science, Multidisciplinary
Yoon Jang Chung, C. Wang, S. K. Singh, A. Gupta, K. W. Baldwin, K. W. West, M. Shayegan, L. N. Pfeiffer, R. Winkler
Summary: This paper reports the fabrication of ultra-high-quality (001) GaAs 2D hole systems with significantly improved mobility values. High-order fractional quantum Hall states and a deep minimum in the magnetoresistance were observed in the measurements.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
A. Shetty, F. Sfigakis, W. Y. Mak, K. Das Gupta, B. Buonacorsi, M. C. Tam, H. S. Kim, I Farrer, A. F. Croxall, H. E. Beere, A. R. Hamilton, M. Pepper, D. G. Austing, S. A. Studenikin, A. Sachrajda, M. E. Reimer, Z. R. Wasilewski, D. A. Ritchie, J. Baugh
Summary: The effects of illumination on undoped two-dimensional electron gases (2DEGs) of varying depths at low temperature are investigated. Unbiased illuminations result in a gain in mobility at a certain electron density for 2DEGs located farther away from the surface, while for 2DEGs closer to the surface, a loss in mobility is observed. Biased illuminations with positive gate voltages lead to a mobility gain, whereas those with negative gate voltages result in a mobility loss. The magnitude of the mobility gain/loss weakens with increasing depth of the 2DEG. These changes in mobility are reversible through another biased illumination with the appropriate gate voltage, provided both n-type and p-type Ohmic contacts are present. Experimental results are modeled using Boltzmann transport theory, and possible mechanisms are discussed.
Article
Physics, Multidisciplinary
Yu A. Pusep, M. D. Teodoro, V Laurindo Jr, E. R. Cardozo de Oliveira, G. M. Gusev, A. K. Bakarov
Summary: The diffusion of photogenerated holes in a high-mobility mesoscopic GaAs channel is studied, and it is found that the injection of holes leads to the formation of a hydrodynamic three-component mixture consisting of electrons and photogenerated heavy and light holes.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Fabio Caruso, Patrick Amsalem, Jie Ma, Areej Aljarb, Thorsten Schultz, Marios Zacharias, Vincent Tung, Norbert Koch, Claudia Draxl
Summary: Experimental and theoretical evidence of strong electron-plasmon interaction in n-doped single-layer MoS2 has been reported. The emergence of distinctive signatures of polaronic coupling in the electron spectral function was revealed through angle-resolved photoemission spectroscopy measurements. Calculations based on many-body perturbation theory illustrated that electronic coupling to two-dimensional carrier plasmons provides an exhaustive explanation of the experimental spectral features and their energies.
Article
Physics, Multidisciplinary
Ziyu Liu, Ursula Wurstbauer, Lingjie Du, Ken W. West, Loren N. Pfeiffer, Michael J. Manfra, Aron Pinczuk
Summary: This study investigates the impacts of domain textures on low-lying neutral excitations in bulk fractional quantum Hall effect (FQHE) systems using resonant inelastic light scattering. The research demonstrates that large domains of quantum fluids support long-wavelength neutral collective excitations with well-defined wave vector dispersion, which can be explained by theories for uniform phases. The accessibility of dispersive low-lying neutral collective modes, such as long wavelength magnetorotons at filling factor v = 1/3, in large domains of FQHE fluids offers significant experimental access to strong electron correlation physics in the FQHE.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
V Ardizzone, F. Riminucci, S. Zanotti, A. Gianfrate, M. Efthymiou-Tsironi, D. G. Suarez-Forero, F. Todisco, M. De Giorgi, D. Trypogeorgos, G. Gigli, K. Baldwin, L. Pfeiffer, D. Ballarini, H. S. Nguyen, D. Gerace, D. Sanvitto
Summary: This study discovered bound states in the continuum (BICs) in a planar photonic crystal lattice, which have a long lifetime and are not affected by radiation. The researchers also demonstrated non-equilibrium Bose-Einstein condensation occurring in the BIC. By combining bosonic condensation and symmetry-protected radiation eigenmodes, they showed a way to impart topological properties onto macroscopic quantum states.
Article
Physics, Multidisciplinary
Sankar Das Sarma
Summary: Majorana particles, which are the same as their antiparticles, show promise for quantum computing in condensed matter systems. This article discusses the search for Majorana modes in semiconductor heterostructures and the limitations imposed by disorder. Majorana zero modes are emergent phenomena in topological superconductors, and this Perspective provides an overview of their physics, recent experimental progress, and future outlook for success.
Article
Physics, Multidisciplinary
DinhDuy Vu, Sankar Das Sarma
Summary: An ergodic system subjected to an external periodic drive will be heated to infinite temperature, but this heating can be stopped during a prethermal period if the applied frequency is larger than the typical energy scale of the local Hamiltonian. This prethermal period exhibits an emergent symmetry that, if broken, leads to subharmonic oscillation of the discrete time crystal (DTC). The presence of dissipation affects the survival time of the prethermal DTC, with a bath coupling prolonging the prethermal period and interaction with the environment destabilizing spontaneous symmetry breaking, resulting in a nonmonotonic variation of the survival time.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Jiabin Yu, Ming Xie, Fengcheng Wu, Sankar Das Sarma
Summary: Signatures of nematic nodal superconductivity have been observed in magic angle twisted bilayer graphene. Researchers propose a general topological mechanism explaining how nematic pairing leads to nodal superconductivity in this material.
Article
Materials Science, Multidisciplinary
Prathyush P. Poduval, Sankar Das Sarma
Summary: We theoretically investigate the issue of doping induced insulator to metal transition in bulk semiconductors by analyzing the density-dependent mean free path and the Anderson localization transition controlled by the Ioffe-Regel-Mott (IRM) criterion. We calculate the mean free path on the highly doped metallic side considering carrier scattering by ionized dopants. The Coulomb disorder of the charged dopants is screened by the carriers themselves, leading to an integral equation for localization. By solving this equation analytically and numerically, we provide detailed results for the critical density of the doping induced metal-insulator transition.
Article
Materials Science, Multidisciplinary
Nathan L. Foulk, Sankar Das Sarma
Summary: We demonstrate the potential realization of quantum Floquet matter, particularly the discrete time crystal (DTC), using modern silicon spin qubits based in quantum dots. This is significant as silicon spin qubits have advantages in dealing with charge noise. We show the differences between prethermal phenomena and true time-crystalline spatiotemporal order, and illustrate rich regime structures in a spin chain of four qubits that are distinct from the thermal regime.
Article
Materials Science, Multidisciplinary
Seth M. Davis, Yang-Zhi Chou, Fengcheng Wu, Sankar Das Sarma
Summary: We calculate the theoretical contribution of scattering by acoustic phonons to the doping and temperature dependence of electrical resistivity in Bernal bilayer graphene (BBG) and rhombohedral trilayer graphene (RTG). The nontrivial geometric features of the band structures of these systems strongly influence the resistivity's temperature and doping dependencies. Our focus on BBG and RTG is motivated by recent experiments in these systems that have discovered exotic low-temperature superconductivity. The understanding of the influence of band geometry on transport is crucial in these systems.
Article
Materials Science, Multidisciplinary
Haining Pan, Sankar Das Sarma
Summary: Motivated by the presence of Majorana zero modes in both the Kitaev chain model and the experimental semiconductor-superconductor Majorana nanowire, this theoretical study investigates the equivalence or similarity between the two models from the perspective of their corresponding dual spin models. By using the Jordan-Wigner transformation, the duality between the Kitaev chain and the transverse-field XY spin model is established, aiming to connect the Kitaev chain and the nanowire. The application of the Jordan-Wigner transformation to the nanowire reveals that the corresponding bosonic spin model is a generalized spin cluster model with staggered couplings. By projecting out the higher energy band of the spinful nanowire system, an effective low-energy spinless system is obtained, leading to the connection between the Kitaev chain and Majorana nanowire.
Article
Materials Science, Multidisciplinary
Yi-Ting Tu, Sankar Das Sarma
Summary: We analyze an experimental work which shows the failure of the Wiedemann-Franz law in graphene at low temperatures, attributing this failure to the non-Fermi liquid nature of the Dirac fluid. Despite theoretical efforts, the observations remain unexplained. Our analysis suggests that the opening of a gap at the Dirac point induced by the substrate may explain the results. Further experiments are needed to resolve the issue and determine the role of electron and hole transport in the presence of disorder and phonons.
Article
Materials Science, Multidisciplinary
Yi-Ting Tu, DinhDuy Vu, S. Das Sarma
Summary: Coupling a one-dimensional quasiperiodic interacting system to a Markovian bath, this study investigates the avalanche instability of the many-body localized phase numerically. The results show that many-body localization (MBL) is more stable in pseudorandom quasiperiodic systems than in randomly disordered systems for a disorder strength W > 8, potentially up to arbitrarily large system sizes. Real-space RG arguments support this conclusion and a detailed comparison between quasiperiodic and random MBL from the avalanche instability perspective reveals that they belong to different universality classes.
Article
Materials Science, Multidisciplinary
Donovan Buterakos, Sankar Das Sarma
Summary: We discuss interesting phenomena in the Hubbard model related to flat-band ferromagnetism. The first is a mathematical theorem that describes the conditions for degeneracy between a flat-band ferromagnetic and a nonferromagnetic state. This theorem is generally applicable and independent of geometry, but only holds for a small number of holes in a filled band. The second phenomenon challenges intuition by showing an example where particles do not prefer to doubly occupy low-energy states before filling higher-energy states. Lastly, we present a pattern of ferromagnetism in small pentagonal and hexagonal plaquettes at specific filling factors. These examples can be observed in quantum dot arrays available in laboratories.
Article
Materials Science, Multidisciplinary
Yang-Zhi Chou, Fengcheng Wu, Jay D. Sau, Sankar Das Sarma
Summary: We investigate the competition between acoustic phonon mediated superconductivity and the long-range Coulomb interaction in moireless graphene multilayers. Our theory explains recent experimental findings in Bernal bilayer graphene and rhombohedral trilayer graphene, and predicts the existence of superconductivity in ABCA tetralayer graphene. The inclusion of realistic band structures with Van Hove singularities and Coulomb repulsion effects in our theory is crucial. Our work provides detailed predictions for graphene superconductivity induced by electron-acoustic phonon interaction, which should be investigated in future experiments.
Article
Materials Science, Multidisciplinary
Robert E. Throckmorton, S. Das Sarma
Summary: This study determines the decoherence time in a system of exchange-coupled electronic spin qubits by calculating the return probability. The multiqubit geometry is found to play a crucial role in the decoherence time.
Article
Materials Science, Multidisciplinary
Seongjin Ahn, Sankar Das Sarma
Summary: This theoretical study validates the experimentally observed sudden change in 2D resistivity with a spontaneous valley polarization transition from 2 to 1 at the critical density, showing quantitative consistency between the two.
