Interplay of screening and superconductivity in low-dimensional materials

TL;DR

This study develops a quantitative model for Coulomb interactions in 2D superconductors, showing that external screening effects are limited and cannot induce unconventional superconductivity in MoS2 solely through substrate tuning.

Contribution

It provides a detailed analysis of screening effects in 2D materials and demonstrates the limited impact of external screening on inducing unconventional superconductivity in MoS2.

Findings

External screening effects are confined within a specific length scale.

Substrate tuning alone cannot induce unconventional Coulomb-driven superconductivity.

Coulomb interactions influence the onset but not the critical temperature of superconductivity.

Abstract

A quantitative description of Coulomb interactions is developed for two-dimensional superconducting materials, enabling us to compare intrinsic with external screening effects, such as those due to substrates. Using the example of a doped monolayer of MoS2 embedded in a tunable dielectric environment, we demonstrate that the influence of external screening is limited to a length scale, bounded from below by the effective thickness of the quasi-two-dimensional material and from above by its intrinsic screening length. As a consequence, it is found that unconventional Coulomb-driven superconductivity cannot be induced in MoS2 by tuning the substrate properties alone. Our calculations of the retarded Morel-Anderson Coulomb potential {\mu *} reveal that the Coulomb interactions, renormalized by the reduced layer thickness and the substrate properties, can shift the onset of the electron-phonon driven superconducting phase in monolayer MoS2 but do not significantly affect the critical temperature at optimal doping.