Elastic backscattering of quantum spin Hall edge modes from Coulomb interactions with non-magnetic impurities

Published on Jun 28, 2021in arXiv: Mesoscale and Nanoscale Physics
· DOI :10.1103/PHYSREVB.103.235164
Max McGinley5
Estimated H-index: 5
 , Nigel R. Cooper53
Estimated H-index: 53
Sources
Abstract
We demonstrate that electrostatic interactions between helical electrons at the edge of a quantum spin Hall insulator and a dynamical impurity can induce quasi-elastic backscattering. Modelling the impurity as a two-level system, we show that transitions between counterpropagating Kramers-degenerate electronic states can occur without breaking time-reversal symmetry, provided that the impurity also undergoes a transition. The associated electrical resistance has a weak temperature dependence down to a non-universal temperature scale. Our results extend the range of known backscattering mechanisms in helical edge modes to include scenarios where electron tunnelling out of the system is absent.
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Aug 27, 2020·Physical Review B4.04
#1Tzu-Chi Hsieh (CU: University of Colorado Boulder)H-Index: 1
#2Yang-Zhi Chou (UMD: University of Maryland, College Park)H-Index: 14
Last. Leo Radzihovsky (CU: University of Colorado Boulder)H-Index: 40
view all 3 authors...
We develop a theory of finite-temperature momentum-resolved tunneling spectroscopy (MRTS) for disordered, interacting two-dimensional topological-insulator edges. The MRTS complements conventional electrical transport measurement in characterizing the properties of the helical Luttinger liquid edges. Using standard bosonization technique, we study low-energy spectral function and the MRTS tunneling current, providing a detailed description controlled by disorder, interaction, and temperature, ta...
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Dec 11, 2019·Physical Review Letters9.16
#1Ajit C. Balram (UCPH: University of Copenhagen)H-Index: 16
#2Karsten Flensberg (UCPH: University of Copenhagen)H-Index: 58
Last. Mark S. Rudner (UCPH: University of Copenhagen)H-Index: 35
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Two-dimensional topological insulators (TIs) host gapless helical edge states that are predicted to support a quantized two-terminal conductance. Quantization is protected by time-reversal symmetry, which forbids elastic backscattering. Paradoxically, the current-carrying state itself breaks the time-reversal symmetry that protects it. Here we show that the combination of electron-electron interactions and momentum-dependent spin-polarization in helical edge states gives rise to feedback through...
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Jan 2, 2019·Physical Review Letters9.16
#1Pietro Novelli (IIT: Istituto Italiano di Tecnologia)H-Index: 4
#2Fabio Taddei (Nest: Nest Labs)H-Index: 24
Last. Marco Polini (University of Manchester)H-Index: 69
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Despite topological protection and the absence of magnetic impurities, two-dimensional topological insulators display quantized conductance only in surprisingly short channels, which can be as short as 100 nm for atomically thin materials. We show that the combined action of short-range nonmagnetic impurities located near the edges and on site electron-electron interactions effectively creates noncollinear magnetic scatterers, and, hence, results in strong backscattering. The mechanism causes de...
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Sep 6, 2018·Physical Review Letters9.16
#1Jukka I. Väyrynen (Microsoft)H-Index: 13
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Time-reversal symmetry suppresses electron backscattering in a quantum-spin-Hall edge, yielding quantized conductance at zero temperature. Understanding the dominant corrections in finite-temperature experiments remains an unsettled issue. We study a novel mechanism for conductance suppression: backscattering caused by incoherent electromagnetic noise. Specifically, we show that an electric potential fluctuating randomly in time can backscatter electrons inelastically without constraints faced b...
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Jan 5, 2018·Science47.73
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#2Valla Fatemi (MIT: Massachusetts Institute of Technology)H-Index: 20
Last. Pablo Jarillo-Herrero (MIT: Massachusetts Institute of Technology)H-Index: 88
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A variety of monolayer crystals have been proposed to be two-dimensional topological insulators exhibiting the quantum spin Hall effect (QSHE), possibly even at high temperatures. Here we report the observation of the QSHE in monolayer tungsten ditelluride (WTe 2 ) at temperatures up to 100 kelvin. In the short-edge limit, the monolayer exhibits the hallmark transport conductance, ~ e 2 / h per edge, where e is the electron charge and h is Planck’s constant. Moreover, a magnetic field suppresses...
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#2Peter StanoH-Index: 25
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We investigate the influence of nuclear spins on the resistance of helical edge states of two-dimensional topological insulators (2DTIs). Via the hyperfine interaction, nuclear spins allow electron backscattering, otherwise forbidden by time reversal symmetry. We identify two backscattering mechanisms, depending on whether the nuclear spins are ordered or not. Their temperature dependence is distinct but both give resistance, which increases with the edge length, decreasing temperature, and incr...
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Experiments showing that a single layer of WTe2 can conduct electricity along its edges while insulating in the interior suggests that this material is a two-dimensional topological insulator.
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We study the helical edge states of a two-dimensional topological insulator without axial spin symmetry due to the Rashba spin-orbit interaction. Lack of axial spin symmetry can lead to so-called generic helical edge states, which have energy-dependent spin orientation. This opens the possibility of inelastic backscattering and thereby nonquantized transport. Here we find analytically the new dispersion relations and the energy dependent spin orientation of the generic helical edge states in the...
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Jun 8, 2015·Physical Review B4.04
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While many of the effects in two-dimensional topological insulators do not depend on the precise edge state structure because of their topological nature, more detailed experimental probes can extract non-topological information. In this paper the authors present comprehensive study of helical edge states of generic quantum spin Hall insulators whose quantization axis rotates as a function of the edge carrier momentum. This analysis reveals the information that can aid the spectroscopic detectio...
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Nov 10, 2021·Physical Review B4.04
#1Oleg M. Yevtushenko (KIT: Karlsruhe Institute of Technology)H-Index: 19
#2V. I. Yudson (HSE: National Research University – Higher School of Economics)H-Index: 10
Dynamical magnetic impurities (MI) are considered as a possible origin for suppression of the ballistic helical transport on edges of 2D topological insulators. The MIs provide a spin-flip backscattering of itinerant helical electrons. Such a backscattering reduces the ballistic conductance if the exchange interaction between the MI and the electrons is anisotropic and the Kondo screening is unimportant. It is well-known that the isotropic MIs do not suppress the helical transport in systems wit...
Source
Theory of optical absorption of linearly and circularly polarized light in surface and edge states in topological insulators is developed for a nonlinear in light intensity regime. The absorbance for surface states and the absorption width for the edge states both decease as 1/\sqrt{I}at high light intensity I Elastic scattering of the photoexcited electrons and holes is taken into account. The absorption bleaching at high intensity is shown to be strongly suppressed by the elastic scatter...
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