Probing Majorana Flat Bands in Nodal $d_{x^2-y^2}$-wave Superconductors with Rashba Spin-Orbit Coupling

TL;DR

This paper demonstrates that Majorana fermions can appear as zero energy modes on the edges of nodal $d_{x^2-y^2}$-wave superconductors with Rashba spin-orbit coupling, and proposes tunnelling spectroscopy as a detection method.

Contribution

It reveals the emergence of Majorana flat bands in nodal superconductors with Rashba coupling and breaking inversion symmetry, and links these to observable tunnelling conductance features.

Findings

Majorana flat bands appear on the [110] edge of nodal superconductors.

Zero bias conductance peaks are induced by Majorana fermions.

Tunnelling spectroscopy can probe Majorana fermions in these materials.

Abstract

We show that Majorana fermions associated with Majorana flat bands emerge as zero energy modes on the [110] edge of single layer or multilayer nodal superconductors with $d_{x^2-y^2}$-wave pairing and Rashba spin-orbit coupling. Moreover, as long as the global inversion symmetry of the single layer or multilayer superconductor is broken, and in the presence of an in-plane magnetic field parallel to the [110] edge, the Majorana fermions together with usual fermionic Andreev bound states induce a triple-peak structure in tunnelling spectroscopy experiments. Importantly, we show that the zero bias conductance peak is induced by Majorana fermions. Therefore, tunnelling spectroscopy can be used to probe Majorana fermions in nodal $d_{x^2-y^2}$-wave superconductors.