Layer-dependent superconducting properties in NbSe₂/MoS₂: Migdal-Eliashberg approach

Utilizing Migdal-Eliashberg theory of superconductivity, we work out the role of electron-phonon coupling (EPC) in guiding superconducting properties of 2D van der Waals heterostructure comprising a single layer of MoS2 and few layers of NbSe2. We find strong EPC and a softening of phonon modes in the lowest acoustic branch. While the single MoS2 layer does not actively contribute to the EPC, it significantly elevates the superconducting critical temperature, Tc compared to monolayer NbSe2. This is attributed to the degradation of the charge-density wave (CDW) by the MoS2 layer. Furthermore, we observe a two-gap superconductivity in NbSe2/MoS2 and extend our study to three layers of NbSe2. A reduction in Tc with increasing thickness of NbSe2 is observed.