Time Reversal Invariant Topological Superconductivity and Majorana Kramers Pairs

TL;DR

This paper proposes a method to engineer time reversal invariant topological superconductors using iron-based superconductors and semiconductors with strong Rashba spin-orbit coupling, predicting Majorana states and novel Josephson effects.

Contribution

It introduces a feasible approach to realize TRI topological superconductors and predicts Majorana Kramers pairs and mirror fractional Josephson effects in such systems.

Findings

Majorana Kramers pairs emerge at boundaries of TRI topological superconductors.

A mirror symmetry protected Majorana quartet leads to a fractional Josephson effect.

Experimental signatures include tunneling spectroscopy during topological phase transitions.

Abstract

We propose a feasible route to engineer one and two dimensional time reversal invariant (TRI) topological superconductors (SC) via proximity effects between nodeless extended s wave iron-based SC and semiconductors with large Rashba spin-orbit interactions. At the boundary of a TRI topological SC, there emerges a Kramers pair of Majorana edge (bound) states. For a Josephson pi-junction we predict a Majorana quartet that is protected by mirror symmetry and leads to a mirror fractional Josephson effect. We analyze the evolution of Majorana pair in Zeeman fields, as the SC undergoes a symmetry class change as well as topological phase transitions, providing an experimental signature in tunneling spectroscopy. We briefly discuss the realization of this mechanism in candidate materials and the possibility of using s and d wave SC and weak topological insulators.