Transport through a quantum spin Hall quantum dot

TL;DR

This paper investigates charge transport in a quantum spin Hall insulator quantum dot with magnetic barriers, analyzing effects of bias, gate voltage, and interactions, and proposing control of edge magnetization via gating.

Contribution

It introduces a quantum-dot structure with magnetic barriers in quantum spin Hall insulators and analyzes transport properties considering interactions and external voltages.

Findings

Partial recurrence of non-interacting behavior at strong interactions

Control of edge magnetization via local gate voltage

Transport characteristics influenced by bias and charging energy

Abstract

Quantum spin Hall insulators, recently realized in HgTe/(Hg,Cd)Te quantum wells, support topologically protected, linearly dispersing edge states with spin-momentum locking. A local magnetic exchange field can open a gap for the edge states. A quantum-dot structure consisting of two such magnetic tunneling barriers is proposed and the charge transport through this device is analyzed. The effects of a finite bias voltage beyond linear response, of a gate voltage, and of the charging energy in the quantum dot are studied within a combination of Green-function and master-equation approaches. Among other results, a partial recurrence of non-interacting behavior is found for strong interactions, and the possibility of controlling the edge magnetization by a locally applied gate voltage is proposed.