Supercurrent-Induced Weyl Superconductivity

TL;DR

This paper demonstrates that applying a supercurrent to noncentrosymmetric, spin-orbit-coupled superconductors with line nodes can induce Weyl superconductivity, leading to topologically protected surface states and controllable gap structures.

Contribution

It introduces a model showing supercurrent-induced transition from line to point nodes and highlights the role of spin-orbit coupling and supercurrent direction in Weyl superconductivity.

Findings

Supercurrent induces a transition from line to point nodes.

Weyl nodes are protected by topological charges.

Surface arc states emerge due to Weyl nodes.

Abstract

We show that Weyl superconductivity can be induced by finite supercurrent in noncentrosymmetric spin-orbit-coupled superconductors with line nodes. We introduce a three-dimensional tight-binding model of a tetragonal superconductor in a $D+p$-wave pairing state with a finite center-of-mass momentum, and elucidate that a line-nodal to point-nodal spectral transition occurs by applying an infinitesimal supercurrent. We also clarify that the higher-order effect in spin-orbit coupling is particularly important for this phenomenon. The point nodes are protected by topologically nontrivial Weyl charges, and therefore gapless arc states appear on the surface of the superconductor. Furthermore, both the positions and the Weyl charges of the point nodes depend on the direction of the current. In addition, a quantized Berry phase defined on high-symmetry planes characterizes the Weyl nodes when the in-plane supercurrent is considered. Our proposition paves a new way for controlling the superconducting gap structures by using an external field.