Monopole Superconductivity in Magnetically Doped Cd$_3$As$_2$

Abstract

When superconducting pairing occurs between Fermi surfaces with different Chern numbers, the Cooper pairs experience a nontrivial pair Berry phase and effective pair monopole charge that enforces nodal monopole harmonic superconducting order beyond the familiar s-, p-, and d-wave superconductors. When magnetically doped, the Dirac semimetal Cd3As2 features Fermi pockets enclosing Weyl nodes with chiralities χ = ±1, ±2. This material serves as a candidate platform for realizing monopole superconductivity with pair monopole charges qp = 1 or 2, depending on the chemical potential. We demonstrate the distinctions in the superconducting phase winding due to pairing with different pair monopole charges and due to pairings in different irreducible representations of the C 4h symmetry of magnetically doped Cd3As2. In all cases, the phase winding patterns are subject to the topologically invariant total phase winding, which depends only on the pair monopole charge and guarantees nodes in the superconducting order for qp > 0.