Rational material design of mixed-valent high T$_c$ superconductors

TL;DR

This paper proposes a new class of thallium halide-based compounds as high-temperature superconductors, predicted via first principles calculations to have T$_c$ up to 30 K with modest doping and pressure, expanding the search for novel superconductors.

Contribution

The study introduces a general first-principles design approach for high T$_c$ superconductors based on non-local correlation-enhanced electron-phonon coupling, exemplified by CsTlF$_3$ and CsTlCl$_3$.

Findings

CsTlF$_3$ and CsTlCl$_3$ predicted to have T$_c$ of 30 K and 20 K.

Superconductivity achievable with modest doping (~0.35/f.u.) and pressure (~10 and 2 GPa).

Design method applicable to discovering other high T$_c$ superconductors.

Abstract

We design, from first principles calculations, a novel family of thallium halide-based compounds as candidates for new high temperature superconductors, whose superconductivity is mediated by the recently proposed mechanism of non-local correlation-enhanced strong electron-phonon coupling. Two prototype compounds namely CsTlF$_3$ and CsTlCl$_3$ are studied with various hole doping levels and volumes. The critical superconducting temperature T$_c$ are predicted to be about 30 K and 20 K with $\sim$0.35/f.u. hole doping and require only modest pressures ($\sim$10 and $\sim$2 GPa), respectively. Our procedure of designing this class of superconductors is quite general and can be used to search for other "other high temperature superconductors".