Tunneling spectroscopy and Josephson current of superconductor-ferromagnet hybrids on the surface of a 3D TI

TL;DR

This paper explores charge transport in superconductor-ferromagnet hybrid junctions on 3D topological insulator surfaces, revealing asymmetric LDOS, subgap resonances, and non-sinusoidal Josephson currents.

Contribution

It presents new insights into the effects of ferromagnetic insulators and normal metal layers on transport properties in topological insulator-based Josephson junctions.

Findings

Asymmetric local density of states in S/N/FI/N' junctions.

Subgap resonant spikes due to finite N layer length.

Non-sinusoidal current-phase relation in S/N/FI/N'/S junctions.

Abstract

We investigate the charge transport property of superconductor (S) /normal metal (N) / ferromagnet insulator (FI) /(normal metal) N' and S/N/FI/N'/S Josephson junctions on a three-dimensional topological insulator surface. We find asymmetric local density of states (LDOSs) in a S/N/FI/N' junction and show that the finite length of the N interlayer gives rise to subgap resonant spikes in the differential conductance and LDOSs. In a S/N/FI/N'/S junction, the Josephson current shows a non-sinusoidal current-phase relation and the N (or N') interlayer decreases the magnitude of the critical current monotonically.