Realizing DIII Class Topological Superconductors using $d_{x^2-y^2}$-wave Superconductors

TL;DR

This paper demonstrates that a quasi-one-dimensional $d_{x^2-y^2}$-wave superconductor with Rashba spin-orbit coupling can host topological superconductivity with Majorana fermions without magnetic fields, broadening potential experimental realizations.

Contribution

It introduces a new class of DIII topological superconductors based on $d_{x^2-y^2}$-wave pairing, eliminating the need for magnetic fields and fine-tuning.

Findings

Supports two Majorana fermions at each end.

Achieves topological phase without magnetic fields.

Applicable over a wide chemical potential range.

Abstract

In this work, we show that a quasi-one-dimensional $d_{x^2-y^2}$-wave superconductor with Rashba spin-orbit coupling is a topological superconductor (TS). This time-reversal invariant DIII class TS supports two topologically protected zero energy Majorana fermions at each end of the system. In contrast to proposals using s-wave superconductors in which a strong magnetic field and the fine tuning of the chemical potential are needed to create Majorana fermions, in our proposal, the topologically non-trivial regime can be reached in the absence of a magnetic field and in a wide range of chemical potential. Experimental signatures and realizations of the proposed superconducting state are discussed.