Emergent superconductivity upon disordering a charge density wave ground state

Abstract

We explore the interplay of a charge density wave (CDW) order and s-wave superconductivity (sSC) in a disordered system. Recent experiments on 1T-TiSe2, where the pristine sample has a commensurate CDW order and the superconductivity appears upon copper intercalation, motivates our study. Starting with an extended Hubbard model, with parameters which yield a CDW ground state within Hartree-Fock-Bogoliubov formalism in pure systems, we show that the addition of disorder quickly wipes out the global charge order by disrupting periodic modulation of density at some (low) strength of disorder. Along with this, the subdominant superconducting order emerges in regions that spatially anti-correlates with islands of strong local CDW order. The short-range density modulations, however, continue to persist and show discernible effects up to a larger disorder strength. The local CDW puddles reduce in size with increasing disorder and they finally lose their relevance in effecting the properties of the system. Our results have strong implications for the experimental phase diagram of transition metal dichalcogenides.

Interplay between charge density wave and superconductivity in multiband systems with interband Coulomb interaction

“…The CDW phase emerges from interband Coulomb interactions and SC is due to an intraband attractive interaction. The moderate strength of the correlations in the materials we are interested justifies our mean-field approach [61,83,84] that makes the problem numerically tractable. Furthermore, we neglected the k-dependence of the hybridization between the bands and of the interactions.…”

“…The many-body problem is approached using a HF meanfield decoupling that has been widely applied to deal with SC and CDW in different models [61,83,84]. We proceed writing the Hamiltonian in the Nambu representation.…”

Interplay between charge density wave and superconductivity in multi-band systems with inter-band Coulomb interaction

“…The CDW phase emerges from inter-band Coulomb interactions and SC is due to an intra-band attractive interaction. The moderate strength of the correlations in the materials we are interested justifies our mean-field approach [60,82,83] that makes the problem numerically tractable. Furthermore, we neglected the k-dependence of the hybridization between the bands and of the interactions.…”

“…The many-body problem is approached using a HF mean-field decoupling that has been widely applied to deal with SC and CDW in different models [60,82,83]. We proceed writing the Hamiltonian in the Nambu representation.…”

Charge, bond, and pair density wave orders in a strongly correlated system

“…Finally, we note that the lines on the temperature axis are purely schematics and are made based on the intensity of orders at T = 0. Thermal and quantum fluctuations can lead to spatial reorganization into domains of finite-Q and Q = 0 orders [62][63][64]. At low doping, the Mott insulator and magnetically ordered states can significantly alter the phase diagram.…”