Superconducting dome in MoS2 and TiSe2 generated by quasiparticle-phonon coupling

TL;DR

This study uses a first-principles model to analyze how electron-electron and electron-phonon interactions shape the superconducting dome in MoS2 and TiSe2, revealing the importance of correlations in accurately predicting Tc.

Contribution

It introduces a comprehensive self-consistent model that accounts for quasiparticle fluctuations, improving the understanding of superconductivity in correlated materials.

Findings

Electron-electron interactions reduce Tc and electron-phonon coupling estimates.

Doping enhances correlations, leading to a superconducting dome.

The model aligns theoretical Tc with experimental observations.

Abstract

We use a first-principles based self-consistent momentum-resolved density fluctuation (MRDF) model to compute the combined effects of electron-electron and electron-phonon interactions to describe the superconducting dome in the correlated MoS2 thin flake and TiSe2. We find that without including the electron-electron interaction, the electron-phonon coupling and the superconducting transition temperature (Tc) are overestimated in both these materials. However, once the full angular and dynamical fluctuations of the spin and charge density induced quasiparticle self-energy effects are included, the electron-phonon coupling and Tc are reduced to the experimental value. With doping, both electronic correlation and electron-phonon coupling grows, and above some doping value, the former becomes so large that it starts to reduce the quasiparticle-phonon coupling constant and Tc, creating a superconducting dome, in agreement with experiments.