Multiband effect in elastoresistance of Fe(Se,Te)

TL;DR

This study explores how elastoresistance varies in Fe(Se,Te) compounds with different electronic properties, revealing a competition between band contributions and phase transitions.

Contribution

It demonstrates the contrasting elastoresistance behaviors in two similar compounds, highlighting the role of electronic structure and phase transitions in elastoresistance.

Findings

First compound's elastoresistance follows 1/T behavior.

Second compound shows sign-reversing elastoresistance.

Elastoresistance in the second compound is modeled by two competing Curie-Weiss terms.

Abstract

We have investigated the elastoresistance of two FeSe${}_{1-x}$Te${}_{x}$ (x about 0.4 - 0.5) compounds that have a close chemical composition but differ significantly in electronic properties. The first compound has a negative temperature coefficient of resistance and does not show any phase transitions other than superconducting. The elastoresistance of this compound approximately follows $1/T$ low as it usually occurs in Fe(Se,S) with metallic conductivity. The second compound has a metallic type of conductivity and in addition to the superconducting transition, there is also a phase transition at a temperature of about 30 K. The elastoresistance of the second compound is sign-reversing and can be approximated with the sum of two Curie-Weiss type terms with opposite signs and different critical temperatures which suggest a competition of contributions to the elastoresistance from different band valleys.