Charge gap and ferroelastic lattice distortion in high-temperature superconductors

TL;DR

This paper explores the connection between ferroelastic lattice distortions and superconducting transitions, highlighting how charge ordering influences high-temperature superconductors and their thermal properties.

Contribution

It introduces the concept that ferroelastic distortions are linked to superconductivity and relates charge gaps to transition temperatures in layered tetragonal superconductors.

Findings

Ferroelastic lattice distortion occurs at the superconducting transition.

High-temperature superconductors exhibit improper ferroelastic distortions caused by charge ordering.

A relation between charge gap and maximum transition temperature is established.

Abstract

It is shown that a ferroelastic lattice distortion is associated with the superconducting transition both in low- and high-temperature superconductors. A low-temperature ferroelastic transition in crystalline solids produces also a maximum in the temperature dependence of their thermal conductivity. In layered tetragonal superconductors with a sufficiently high transition temperature, a ferroelastic distortion is improper and is caused by an out-of-plane charge ordering. The relation between the out-of-plane charge gap and the maximum superconducting transition temperature for these superconductors is obtained.