Thermoelectric transport in junctions of Majorana and Dirac channels

TL;DR

This paper explores thermoelectric effects in a topological insulator junction involving Majorana and Dirac channels, revealing unconventional flux oscillations and flux-dependent current directions.

Contribution

It introduces a model of thermoelectric transport in Majorana-Dirac junctions on topological insulators, highlighting flux oscillations and non-sinusoidal current-flux relationships.

Findings

Electric and heat currents oscillate with a $2\

Thermoelectric effect occurs without a threshold due to gapless Majorana modes.

Electric current direction can reverse depending on magnetic flux.

Abstract

We investigate the thermoelectric current and heat conductance in a chiral Josephson contact on a surface of a 3D topological insulator, covered with superconducting and magnetic insulator films. The contact consists of two junctions of Majorana and Dirac channels next to two superconductors. Geometric asymmetry results in a supercurrent without a phase bias. The interference of Dirac fermions causes oscillations of the electric and heat currents with an unconventional period $2\Phi_0=h/e$ as functions of the Aharonov-Bohm flux. Due to the gapless character of Majorana modes, there is no threshold for the thermoelectric effect and the current-flux relationship is non-sinusoidal. Depending on the magnetic flux, the direction of the electric current can be both from the hot to cold lead and vice versa.