Comparative magnetotransport and Tc measurements on kappa-(BEDT-TTF)2Cu(SCN)2 under pressure

TL;DR

This study investigates how different pressure media affect magnetotransport and Tc measurements in the organic superconductor κ-(BEDT-TTF)₂Cu(SCN)₂, revealing a pressure-medium independent correlation between Tc and Fermi surface properties.

Contribution

It demonstrates that pressure-media dependence influences measurements but the Tc-Fermi surface relationship remains consistent across media, highlighting intrinsic electronic correlations.

Findings

Pressure media affect magnetotransport results due to non-hydrostatic conditions.

A pressure-independent correlation exists between Tc and the quasi 2D Fermi surface pocket size.

Pressure increases carrier density by transferring carriers from quasi 1D to 2D Fermi surface sections.

Abstract

We compare magnetotransport measurements under pressure on the organic superconductor $\kappa$-(BEDT-TTF)$_{2}$Cu(SCN)$_{2}$ with different pressure-media and discover that the results are pressure media dependent. This pressure-medium dependence is thought to originate from the difference in thermal contraction between the very soft and highly anisotropic sample and the isotropically contracting, but solid pressure medium, thus resulting in non-hydrostatic pressure on the sample. However, comparison of pressure measurements with different media reveals a pressure-medium independent correlation between the superconducting transition temperature, T$_{\rm c}$, and the size of the quasi 2-dimensional Fermi surface pocket and thus the quasi 2-dimensional carrier density in $\kappa$-(BEDT-TTF)$_{2}$Cu(SCN)$_{2}$. The observed pressure-induced increase in the quasi 2-dimensional carrier density can be interpreted as a transfer of carriers from quasi 1-dimensional Fermi surface sections, reminiscent of a mechanism in cuprate superconductors, where pressure is known to transfer carriers from the insulating charge reservoir layers into the conducting cuprate sheets.