Shot noise in the edge states of 2D topological insulators

TL;DR

This paper investigates shot noise and resistance in the edge states of 2D topological insulators, considering electron exchange with bulk puddles and different spin relaxation regimes, aligning with experimental observations.

Contribution

It introduces a model accounting for electron exchange with bulk puddles and spin relaxation effects, providing insights into shot noise behavior in 2D topological insulators.

Findings

Fano factor varies from 0 to 1/3 depending on parameters

Shot noise results agree with experimental data

Different spin relaxation regimes significantly affect noise characteristics

Abstract

We calculate the resistance and shot noise in the edge states of a 2D topological insulator that result from the exchange of electrons between these states and conducting puddles in the bulk of the insulator. The two limiting cases where the energy relaxation is either absent or very strong are considered. A finite time of spin relaxation in the puddles is introduced phenomenologically. Depending on this time and on the strength of coupling between the edge states and the puddles, the Fano factor $F=S_I/2eI$ ranges from 0 to 1/3, which is in an agreement with the available experimental data.