Universal enhancement of superconductivity in two dimensional semiconductors at low doping by electron-electron interaction

TL;DR

This paper demonstrates that electron-electron interactions in low-doped two-dimensional semiconductors can significantly enhance superconductivity, explaining experimental observations and guiding the development of high T$_c$ materials.

Contribution

It reveals how electron-electron interactions boost superconductivity in 2D semiconductors at low doping, supported by first-principles calculations beyond DFT.

Findings

Electron-electron interactions enhance valley polarization response.

Superconducting T$_c$ is increased due to electron-electron interactions.

Conditions for maximal T$_c$ enhancement are identified.

Abstract

In two-dimensional multivalley semiconductors, at low doping, even a moderate electron-electron interaction enhances the response to any perturbation inducing a valley polarization. If the valley polarization is due to the electron-phonon coupling, the electron-electron interaction results in an enhancement of the superconducting critical temperature. By performing first principles calculations beyond density functional theory, we prove that this effect accounts for the unconventional doping-dependence of the superconducting transition-temperature (T$_c$) and of the magnetic susceptibility measured in Li$_x$ZrNCl. By finding the conditions for a maximal T$_c$ enhancement, we show how weakly-doped two-dimensional semiconductors provide a route towards high T$_c$ superconductivity.