Weyl superconductivity induced by supercurrent flow

A superconducting gap structure plays an important role in discussing the symmetry of the order parameter and the pairing mechanism in unconventional superconductors. From the theoretical point of view, previous studies have constructed classification methods for predicting the superconducting gap structure by using symmetry and topology for three decades. On the other hand, previous theoretical studies have suggested that topological superconductivity can be realized by applying a Zeeman field or laser light to noncentrosymmetric d-wave superconductors. Furthermore, supercurrent is also considered as a promising external field for controlling gap structures and (topological) quantum states.

Stimulated by the above backgrounds, we propose that Weyl superconductivity can be realized by applying supercurrent to three-dimensional (3D) noncentrosymmetric line-nodal superconductors. We consider a 3D tight-binding model of a tetragonal superconductor in a D+p-wave pairing state with a finite center-of-mass momentum. The original line-nodal structure is modified into a point-nodal one, in which each point node is characterized by a nontrivial Weyl charge, by the cooperating effect of the supercurrent and spin-orbit coupling. 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.