Odd-parity superconductivity in bilayer transition metal dichalcogenides
AbstractSpin-orbit coupling in transition metal dichalcogenides (TMDCs) causes spin-valley locking, giving rise to unconventional optical, transport, and superconducting properties. In this paper, we propose exotic superconductivity in bilayer group-IV TMDCs by symmetry control. The sublattice-dependent “hidden” spin-orbit coupling arising from local inversion symmetry breaking in the crystal structure may stabilize the odd-parity superconductivity by purely s-wave local pairing interaction. The stability of the odd-parity superconducting state depends on the bilayer stacking. The 2Hb stacking in MoX2 and WX2 (X=S,Se) favors the odd-parity superconductivity due to interlayer quantum interference. On the other hand, the odd-parity superconductivity is suppressed by the 2Ha stacking of NbSe2. Calculating the phase diagram of the tight-binding model derived from first-principles band calculations, we conclude that the intercalated bilayer MoS2 and WS2 are candidates for a new class of odd-parity superconductors by spin-orbit coupling.