Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session Y40: Exotic Electron Transport and Polaritons in NanostructuresFocus
|
Hide Abstracts |
Sponsoring Units: DMP Chair: Alexander Balandin, University of California, Riverside; Jeongheon Choe, University of Texas at Austin Room: Room 232 |
Friday, March 10, 2023 8:00AM - 8:36AM |
Y40.00001: Manipulation and topological entanglement of fractionalized injected charge in the metastable state of 1T-TaS2 Invited Speaker: Dragan Mihailovic Metastability of many-body quantum states is rare and poorly understood. An exceptional example of such a state is the low-temperature metallic state of the layered dichalcogenide 1T-TaS2 in which metastable electronic order is frozen after external excitation. Here we investigate the microscopic dynamics of injected charges in the metastable state after photoexcitation or carrier injection in a multiple-tip scanning tunnelling microscope. Remarkably, carrier injection through electrodes and by low-fluence photoexcitation lead to similar structures, indicating a common mechanism. We observe the non-thermal formation of a topologically entangled network of dislocations in the electonic crystal superlattice, joined by domain walls. The annihilation of dislocations follows topological rules, which directly correlates with a change of macroscopic electrical resistance. At higher excitation fluences, an amorphous Wigner glass is formed, which is distinct from the fractionalized charged network forming at lower density. |
Friday, March 10, 2023 8:36AM - 8:48AM |
Y40.00002: Coherent Resonant Tunneling Transport through Non-centrosymmetric GaN/AlN Multi-barrier Heterostructures Jimy Encomendero, Vladimir Protasenko, Debdeep Jena, Grace Xing The recent demonstration of resonant tunneling through double barrier GaN/AlN heterostructures has reignited interest in harnessing this quantum transport regime for ultrafast electronic and photonic devices. In noncentrosymmetric semiconductors, however, quantum confinement results not only in a discontinuous band profile, but also generates built-in polarization charges along the transport direction. Here, using a combined experimental and theoretical approach, we elucidate the important consequences of the built-in polarization fields on the resonant tunneling transport characteristics of multiple-barrier GaN/AlN heterostructures. |
Friday, March 10, 2023 8:48AM - 9:00AM |
Y40.00003: Universality and the thermoelectric transport properties through quantum dots systems: Seeking for conditions that could improve the efficiency Roberto Franco Penaloza Employing universal relations obtained recently for the Onsager coefficients in the linear regime at the symmetric point of the single impurity Anderson model [1], and using the Mahan-Sofo parameter [2], we obtain conditions for the quantum scattering phase shift associated with the asymptotic Carnot’s limit for the thermoelectric efficiency. We show that is impossible with a single Quantum dot at the Kondo regime achieve the conditions that causes the improving of the thermoelectric efficiency. We study a system of two coupled identical quantum dots, without inter-dot correlations and preserving one dot in the electron-hole symmetric point; employing analogies between this system -similar to a quantum dot in the electron-hole symmetric point, immersed in a non-ballistic quantum wire- and the original system -a quantum dot at the symmetric electron-hole point, immersed in a ballistic quantum wire-; we show that is possible to obtain conditions for the quantum phase shift -linked to charge fluctuations in one of the quantum dots- that satisfy the conditions associated with enhance the thermoelectric efficiency in this system, we discuss the presence of quasi-bound states in the continuum associated to the quantum scattering-interference process that improve the efficiency [3]. We describe “anomalies” in the photo-emission spectroscopy and inverse photo-emission spectroscopy that “arise” associated to the conditions that enhance the efficiency in order to guide possible experimental work that submit to the experimental test our theoretical predictions, discussing to possible temperature values and conditions that could be linked with the experimental research of our results. |
Friday, March 10, 2023 9:00AM - 9:12AM |
Y40.00004: Accumulation-mode single-electron pumping in undoped GaAs Stephen R Harrigan, Francois Sfigakis, Arjun Shetty, Lin Tian, Nachiket Sherlekar, HoSung Kim, Alan Tam, Zbigniew Wasilewski, Michael Reimer, Jonathan D Baugh Single-electron pumps (SEP) have demonstrated quantized charge pumping at frequencies beyond 1 GHz and temperatures up to 17 K [1]. Recently, a non-adiabatic SEP integrated with a lateral p-n junction in a direct band gap semiconductor has been proposed as a single-photon source (SPS) [2]. The SEP injects individual electrons into a 2D hole gas, forming electrically-driven excitons that recombine to emit single photons. Provided that the electron injection rate is slower than the exciton lifetime, single-photon pulses will not overlap. Undoped AlGaAs/GaAs heterostructures are a promising platform for such a SPS, as they have ultra-high mobilities, excellent reproducibility between cooldowns, and ambipolar Ohmic contacts can be fabricated [3]. |
Friday, March 10, 2023 9:12AM - 9:24AM |
Y40.00005: Nonlinear current-voltage characteristics of mesoscopic structures in non-equilibrium ballistic transport Jean J Heremans, G. Kataria, A. Gupta, Mani Chandra, R. Sundararaman, S. Fallahi, G. Gardner, M. J Manfra Advances in materials have allowed for the suppression of momentum relaxing electron-phonon and defect scattering in very clean material systems such as graphene and semiconductor heterostructure based 2D electron systems (2DESs). This has led to the study of the hydrodynamic and ballistic transport regimes where the dominant interactions in the system are electron-electron scattering and electron-device wall collisions. We consider mesoscopic structures in an ultra-high mobility GaAs/AlGaAs 2DES initially in the ballistic regime at low temperature. Increasing the bias current across the structures can result in heating of the electron system due to injection of high energy electrons. This leads to a ballistic-hydrodynamic regime transition, which manifests itself as a deviation from linearity in the current-voltage characteristics of the structures. We present nonlinear current-voltage characteristics in both 2- and 4-probe configurations in several progressively complex mesoscopic geometries and point contacts under non-equilibrium transport. The possible origin of the nonlinearities and their association with the Gurzhi hydrodynamic effect will be discussed. |
Friday, March 10, 2023 9:24AM - 9:36AM |
Y40.00006: Inverse Design of Semiconductor Heterostructures Using First-Principles Modelling and Machine Learning Approaches Sanghamitra Neogi, Artem Pimachev Nanofabrication techniques have attained great control over the growth of the seminconductor Heterostructures. Nevertheless, the fabricated materials are strongly affected by the growth process, and their structural properties show high variability. It is essential to acquire a comprehensive understanding of the relationship between structural parameters and electronic properties of materials, to optimize their performance. Ab initio computational approaches enable prediction of materials properties with minimal experimental input; however, these approaches often require large computational costs. It remains a challenge to model electronic properties of technologically relevant heterostructures incorporating full structural complexity, stemming from the vast fabrication dependent parameter space. In this talk, I will discuss our machine learning (ML) based approaches that extend the applicability of ab initio techniques for predicting electronic properties of fabricated heterostructures. We develop an inverse approach that predicts the structural features of a given heterostructure for target electronic band structures. We train the ML models with first-principles electronic property data of silicon/germanium superlattices of varied period and composition. We use structural descriptors and unfolded effective band structures or spectral functions as training data. I will discuss the importance of accurate identification of local structural features on the performance of our ML models. This approach establishes a direct connection between experimental and theoretical results. For example, our model predicts the atomic scale structural data of the system that results in a given spectra obtained with ARPES techniques. We provide the ARPES image of bulk Si and δ-doped Si as input. Our inverse approach successfully converts the data into a set of structural and atomic features necessary to describe the bulk systems. The ML models reveals key physical insights regarding the relationships between atomic configurations and their contributions to electronic properties. |
Friday, March 10, 2023 9:36AM - 9:48AM |
Y40.00007: Transport Properties of Polarization-Induced 2D Electron Gases in Epitaxial AlScN/GaN Heterojunctions Thai-Son Nguyen, Joseph Casamento, Chandrashekhar Savant, Yongjin Cho, Huili Grace Xing, Debdeep Jena AlScN is an attractive epitaxial heterostructure barrier for GaN high electron mobility transistors (HEMTs) due to its strong spontaneous and piezoelectric polarizations, larger dielectric constant than AlN [Appl. Phys. Lett. 120, 152901 (2022)], and the ability to be lattice-matched with GaN [Appl. Phys. Lett. 110, 162104 (2017)]. We report the epitaxial growth of AlScN/GaN heterostructures by plasma-assisted molecular beam epitaxy (MBE) and the study of transport characteristics of the polarization-induced 2D electron gases (2DEGs) using temperature-dependent magnetotransport measurement. By varying the thickness of lattice-matched AlScN on GaN, 2DEGs with high (~ 2 x 1013/cm2) and tunable carrier densities were achieved. The 2DEG formed at AlScN-GaN direct heterojunction exhibits mobilities ~ 300 cm2/V.s between 10 K and 300 K, comparable to those in Si MOSFETs. The insertion of a 2 nm AlN interlayer boosts the 2DEG mobility by more than five times to 1573 cm2/V.s at 300 K and by more than twenty times to 6980 cm2/V.s at 10 K, both are among the highest values reported to date. Theoretical modeling of the temperature-dependent Hall-effect mobilities shows that electron transport is limited by polar optical phonon scattering at temperatures above 200 K and interface roughness scattering at lower temperatures. The ability to epitaxially grow AlScN/GaN HEMTs with high electron mobility and tunable carrier density enables the merging of promising physical properties of epitaxial AlScN with established nitride semiconductors. |
Friday, March 10, 2023 9:48AM - 10:00AM |
Y40.00008: Universality classes of the Anderson transitions driven by quasiperiodic potential in the three-dimensional Wigner-Dyson symmetry classes Tomi Ohtsuki, Xunlong Luo A quasiperiodic system is an intermediate state between periodic and disordered systems with a unique delocalization-localization transition driven by the quasiperiodic potential (QP). One of the intriguing questions is whether the universality class of the Anderson transition (AT) driven by QP is similar to that of the AT driven by the random potential in the same symmetry class. Here, we study the critical behavior of the ATs driven by QP in the three-dimensional (3D) Anderson model, the Peierls phase model, and the Ando model, which belong to the Wigner-Dyson symmetry classes. The localization length and two-terminal conductance have been calculated using the transfer-matrix method, and we argue that their error estimations in statistics suffer from the correlation of QP. With the correlation under control, the critical exponents ν of the ATs driven by QP are estimated by the finite-size scaling analysis of conductance, and they are consistent with the exponents ν of the ATs driven by the random potential. Moreover, the critical conductance distribution and the level spacing ratio distribution have been studied. We also find that a convolutional neural network trained by the localized/delocalized wave functions in a disordered system predicts the localization/delocalization of the wave functions in quasiperiodic systems. Our numerical results strongly support the idea that the universality classes of the ATs driven by QP and the random potential are similar in the 3D Wigner-Dyson symmetry classes. |
Friday, March 10, 2023 10:00AM - 10:12AM |
Y40.00009: Driven-dissipative charge transport in small networks: negative conductance and light-induced currents. Felipe A Recabal, Felipe F Herrera Nanojunction experiments with single molecules or quantum dots placed between macroscopic leads allow the exploration of quantum transport at the nanoscale [1]. We model these systems adopting a Markovian open-quantum system approach to compute the current-voltage response of small-size networks of interacting two-level conducting sites that are coupled to leads, and radiative and non-radiative reservoirs [2]. We model the phenomenon of light-induced current, reported theoretically and experimentally. We validate our Markovian model by reproducing the experimental results on negative conductance [3] of single-molecule junctions with a two-site model in the absence of electromagnetic driving. We show that Coulomb blocking of current can be neglected with an external electromagnetic driving source and non-radiative decay. At zero bias voltage, the direction of the photocurrent induced by the electromagnetic driving source depends on the type of delocalized orbital. We also discuss the possibility of tuning electron transport in infrared cavities under vibrational strong coupling [4] and suggest experiments that can verify our predictions. |
Friday, March 10, 2023 10:12AM - 10:24AM |
Y40.00010: A Highly Scalable NEGF Solver for Modeling Time-Dependent Quantum Transport in Nanomaterials Saurabh S Sawant, Jackie Yao, Revathi Jambunathan, Francois Leonard, Andy Nonaka Advances in nanotechnology are enabling breakthroughs in miniaturized photon detectors, which will, in turn, have a tremendous impact on numerous scientific undertakings, such as the identification of remote galaxies and biomedical imaging. Such devices make use of highly conductive nanomaterials such as graphene or carbon nanotubes that are functionalized with photoactive molecules or quantum dots, which absorb photons of particular wavelength depending on their size and generate exciton pairs that dissociate at the interface of these nanomaterials. Either a hole or electron of the exciton pair is transferred to the transport channel, while the leftover charge modulates the electrostatic surface potential and affects the current. Quantum transport through these nanomaterials can be accurately characterized using the time-dependent non-equilibrium Green's function method that must be self-consistently coupled with Poisson's equations. In this work, we present an open-source, GPU-accelerated software framework to solve these equations and demonstrate its scaling on manycore/GPU architectures. The core of the solver is built on top of the AMReX library, which provides support for highly scalable applications employing structured grid implementations. |
Friday, March 10, 2023 10:24AM - 10:36AM |
Y40.00011: Gate-induced Metallic Transition in Colloidal Quantum Dots Superlattice Ricky D Septianto, Retno Miranti, Takaaki Hikima, Nobuhiro Matsushita, Yoshihiro Iwasa, Satria Z Bisri The quantum confinement properties of colloidal quantum dots (QDs) make them emerge as a new class exhibiting intriguing properties, creating artificial giant atoms that can be assembled into coherent superstructures. Controlling individual colloidal QD into superlattice assembly can give rise to novel emerging properties stemming from the collective phenomena, different from the properties of their bulk materials and the isolated QDs. Therefore, systematically understanding the charge transport mechanism in a very clean system of QD assemblies is crucial. Here we demonstrate a fascinating transition from insulating to metallic behavior on lead sulfide (PbS) colloidal QDs. This observation can be attained due to the perfection of the methods to form giant superlattices of epitaxially-connected PbS QDs, in which highly-coherent atomic lattice and minimum energetic disorder are achieved. The induction of extremely high carrier density in these QD-SLs utilizing the electric-double-layer transistor (EDLT) can significantly shift the Fermi level energy, and we can surpass the predicted critical carrier density to achieve metallicity that allows high conductance. This finding will promote QD-SLs as the next-generation platforms for quantum materials and advance the present functionalizations of these low-dimensional materials in optoelectronic devices. |
Friday, March 10, 2023 10:36AM - 10:48AM Author not Attending |
Y40.00012: Spatially-Complex 2D/3D Geometries and Boundary Conditions in Electron Hydrodynamics Georgios Varnavides, Adam S Jermyn, Prineha Narang Recent advances in spatially-resolved transport measurements and computational frameworks have revealed that electrons in condensed matter can flow collectively, confirming early theoretical predictions and reinvigorating scientific interest in the field of electron hydrodynamics. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700