Topological D+p-wave superconductivity in Rashba systems

TL;DR

This paper demonstrates the existence of topological superconductivity in d-wave superconductors on substrates, revealing robust nontrivial properties and identifying potential materials like cuprates and heavy-fermion compounds as candidates.

Contribution

It introduces the concept of topological phases in d-wave superconductors under magnetic fields and identifies noncentrosymmetric heavy-fermion SCs as Weyl superconductors.

Findings

D-wave SCs can host topological phases with nontrivial Chern numbers.

High-temperature cuprate SCs on substrates can exhibit topological superconductivity.

Noncentrosymmetric d-wave SCs can be Weyl SCs with protected Weyl nodes.

Abstract

We show two-dimensional "strong" topological superconductivity in d-wave superconductors (SCs). Although the topological invariant of the bulk wave function cannot be defined in d_{x^2-y^2}-wave and d_{xy}-wave SCs because of nodal excitations, the bulk energy spectrum of d-wave SCs on a substrate is fully gapped in a magnetic field. Then the superconducting state is specified by a nontrivial Chern number, and hence topologically nontrivial properties are robust against disorders and interactions. We discuss high-temperature topological superconductivity in cuprate SCs recently fabricated on a substrate. Furthermore, we show that the three-dimensional noncentrosymmetric d-wave SC is a Weyl SC hosting topologically protected Weyl nodes. Noncentrosymmetric heavy-fermion SCs, such as CeRhSi_3 and CeIrSi_3, are candidates for Weyl SCs.