Emergent superconductivity upon disordering a charge density wave ground state

TL;DR

This study investigates how disorder affects the competition between charge density wave order and s-wave superconductivity, revealing that disorder suppresses CDW and induces localized superconductivity, with implications for transition metal dichalcogenides.

Contribution

We demonstrate that disorder destroys long-range CDW order and promotes local superconducting regions, providing new insights into the phase diagram of related materials.

Findings

Disorder quickly destroys global CDW order.

Superconductivity emerges in regions anti-correlated with CDW islands.

Short-range CDW modulations persist at higher disorder levels.

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-TiSe_2, 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.