Intrinsic topological superconductivity with exactly flat surface bands in the quasi-one-dimensional A${}_2$Cr${}_3$As${}_3$ (A=Na, K, Rb, Cs) superconductors

Cheng-Cheng Liu, Chen Lu, Li-Da Zhang +3

A spin-U(1)-symmetry protected momentum-dependent integer-$Z$-valued topological invariant is proposed to time-reversal-invariant (TRI) superconductivity (SC) whose nonzero value w…