Heat Conduction in $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$

TL;DR

This paper reports the first measurements of thermal conductivity in a quasi-two-dimensional organic superconductor, revealing features similar to cuprates and providing insights into unconventional superconductivity.

Contribution

It presents novel experimental data on thermal conductivity in $$-(BEDT-TTF)$_2$X, highlighting features analogous to cuprates and supporting theories of unconventional superconductivity.

Findings

Superconductivity onset causes a sudden increase in thermal conductivity.

Moderate magnetic fields suppress the thermal conductivity increase.

A finite residual linear term in thermal conductivity aligns with unconventional superconductor theories.

Abstract

The first study of thermal conductivity, $\kappa$, in a quasi-two-dimensional organic superconductor of the $\kappa$-(BEDT-TTF)$_2$X family reveals features analogous to those already observed in the cuprates. The onset of superconductivity is associated with a sudden increase in $\kappa$ which can be suppressed by the application of a moderate magnetic field. At low temperatures, a finite linear term - due to a residual electronic contribution- was resolved. The magnitude of this term is close to what is predicted by the theory of transport in unconventional superconductors.