Topological d-wave Superconductivity in Cuprate Thin Films*

Topological superconductivity (TSC) is an intriguing phase of matter. In particular, TSC in noncentrosymmetric (NCS) systems attract much attention. For instance, s-wave superconductors (SCs) with Rashba spin-orbit coupling (SOC) are shown to be TSC under Zeeman field, although centrosymmetric s-wave SCs are topologically trivial [1]. Further research on NCS TSC may yield novel topological phenomena, and is an urgent issue.
TSC requires bulk excitation gap, and for this reason, d-wave SCs have not been considered as a platform for TSC. Here we propose that 2D nodal d-wave SCs with Rashba SOC open the bulk gap and become TSC under Zeeman field [2,3]. The TSC belongs to class D, and host chiral edge states. Such a system may be realized in heterostructures of ferromagnets and cuprate SCs. We also discuss 3D generalization to Weyl superconductivity in 3D nodal NCS SCs under Zeeman field.
[1] M. Sato and S. Fujimoto, J. Phys. Soc. Jpn. 85, 072001 (2016)
[2] T. Yoshida and Y. Yanase, Phys. Rev. B 93, 054504 (2016)
[3] A. Daido and Y. Yanase, Phys. Rev. B 94, 054519 (2016)