In-situ electrical and thermal transport properties of FeySe1-xTex films with ionic liquid gating

TL;DR

This study investigates how ionic liquid gating affects the electrical and thermal transport properties of FeySe1-xTex films, revealing enhanced superconductivity and novel scaling behaviors linked to spin fluctuations.

Contribution

It introduces in-situ measurements combined with ionic liquid gating to uncover new scaling laws and transport mechanisms in FeySe1-xTex superconductors.

Findings

Ionic gating raises Tc and alters Seebeck coefficient behavior.

Seebeck coefficient exhibits a logarithmic temperature dependence.

A relationship between resistivity slope and Tc is established.

Abstract

We combine in-situ electrical transport and Seebeck coefficient measurements with the ionic liquid gating technique to investigate superconductivity and the normal state of FeySe1-xTex (FST) films. We find that the pristine FST films feature a non-Fermi liquid temperature dependence of the Seebeck coefficient, i.e., S/T ~ AS lnT, and AS is strongly correlated with the superconducting transition temperature (Tc). Ionic liquid gating significantly raises Tc of FST films, for which the Seebeck coefficient displays a novel scaling behavior and retains the logarithmic temperature dependence. Moreover, a quantitative relationship between the slope of T-linear resistivity (A\r{ho}) and Tc for gated films is observed, i.e., (A\r{ho})1/2 ~ Tc, consistent with previous reports on cuprates and FeSe. The scaling behaviors of AS and A\r{ho} point to a spin-fluctuation-associated transport mechanism in gated FeySe1-xTex superconductors.