Competition between superconductivity and charge density wave in multiband intermetallic systems

We investigate the interplay between superconductivity (SC) and charge density wave (CDW) in a two-band model system in a square lattice. Our main goal is to describe intermetallic systems with a d-band of moderately correlated electrons coexisting with a large sp-band, for which a mean-field approximation is adequate. For simplicity, all interactions and the hybridization are considered site-independent. We obtain the eigenvalues of the Hamiltonian numerically and minimize the free energy density with respect to the relevant parameters to obtain the phase diagrams. We analyze two different types of superconducting ground states coexisting with the CDW, i.e., a homogeneous SC ground state and a pair density wave where the SC order parameter has the same spatial modulation of the CDW. Our results [1] show that the CDW and SC orders compete, but depending on the parameters of the model these phases might coexist.

[1] Nei Lopes, Daniel Reyes, Mucio A. Continentino, and Christopher Thomas, Physical Review B, 103, 195150 (2021).