Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNontrivial interplay of strong disorder and interactions in quantum spin-Hall insulators doped with dilute magnetic impurities
113
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We investigate nonperturbatively the effect of a magnetic dopant impurity on the edge transport of a quantum spin Hall (QSH) insulator. We show that for a strongly coupled magnetic dopant located near the edge of a system, a pair of transmission anti-resonances appear. When the chemical potential is on resonance, interaction effects broaden the anti-resonance width with decreasing temperature, thus suppressing transport for both repulsive and moderately attractive interactions. Consequences for the recently observed QSH insulating phase of the $1$-T$^{prime}$ of WTe$_2$ are briefly discussed.
rate research
Read More
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.
The fabrication of bismuthene on top of SiC paved the way for substrate engineering of room temperature quantum spin Hall insulators made of group V atoms. We perform large-scale quantum transport calculations in these 2d materials to analyse the rich phenomenology that arises from the interplay between topology, disorder, valley and spin degrees of freedom. For this purpose, we consider a minimal multi-orbital real-space tight-binding hamiltonian and use a Chebyshev polynomial expansion technique. We discuss how the quantum spin Hall states are affected by disorder, sublattice resolved potential and Rashba spin-orbit coupling.
Short-range electron-electron interactions are incorporated into the network model of the integer quantum Hall effect. In the presence of interactions, the electrons, propagating along one link, experience exchange scattering off the Friedel oscillations of the density matrix of electrons on the neighboring links. As a result, the energy dependence of the transmission, ${cal T}(epsilon)$, of the node, connecting the two links, develops an anomaly at the Fermi level, $epsilon=epsilon_F$. We show that this interaction-induced anomaly in ${cal T}(epsilon)$ translates into the anomalous behavior of the Hall conductivity, $sigma_{xy}( u)$, where $ u$ is the filling factor (we assume that the electrons are {em spinless}). At low temperatures, $T to 0$, the evolution of the quantized $sigma_{xy}$ with decreasing $ u$ proceeds as $1to 2 to 0$, in apparent violation of the semicircle relation. The anomaly in ${cal T}(epsilon)$ also affects the temperature dependence of the peak in the diagonal conductivity, $sigma_{xx}( u, T)$. In particular, unlike the case of noninteracting electrons,the maximum value of $sigma_{xx}$ stays at $sigma_{xx} = 0.5$ within a wide temperature interval.
We analyze the magnetic and transport properties of a double quantum dot coupled to superconducting leads. In addition to the possible phase transition to a $pi$ state, already present in the single dot case, this system exhibits a richer magnetic behavior due to the competition between Kondo and inter-dot antiferromagnetic coupling. We obtain results for the Josephson current which may help to understand recent experiments on superconductor-metallofullerene dimer junctions. We show that in such a system the Josephson effect can be used to control its magnetic configuration.
We study the disorder effect of resonant spin Hall effect in a two-dimension electron system with Rashba coupling in the presence of a tilted magnetic field. The competition between the Rashba coupling and the Zeeman coupling leads to the energy crossing of the Landau levels, which gives rise to the resonant spin Hall effect. Utilizing the Stredas formula within the self-consistent Born approximation, we find that the impurity scattering broadens the energy levels, and the resonant spin Hall conductance exhibits a double peak around the resonant point, which is recovered in an applied titled magnetic field.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
