Significant change in the electronic behavior associated with structural distortions in the single crystalline SrAg4As2

TL;DR

This study investigates how structural distortions in SrAg4As2 influence its electronic properties, revealing phase transitions, Fermi surface changes, and the absence of superconductivity up to high pressures.

Contribution

It provides new insights into the relationship between structural distortions and electronic behavior in SrAg4As2, highlighting Fermi surface topology changes and phase transition characteristics.

Findings

Phase transition around 110 K with resistivity and heat capacity anomalies

Fermi surface topology significantly altered by structural distortion

No superconductivity observed down to 2 K under high pressure

Abstract

We report a combined study of transport and thermodynamic measurements on the layered pnictide material SrAg4As2. Upon cooling, a drop in electrical and Hall resistivity, a jump in heat capacity and an increase in susceptibility and magnetoresistance (MR) are observed around 110 K. These observations suggest that non-magnetic phase transitions emerge at around 110 K, that are likely associated with structural distortions. In sharp contrast with the first-principles calculations based on the crystal structure at room temperature, quantum oscillations reveal small Fermi pockets with light effective masses, suggesting a significant change in the Fermi surface topology caused by the low temperature structural distortion. No superconductivity emerges in SrAg$_4$As$_2$ down to 2 K and under pressures up to 2.13 GPa; instead, the low temperature structural distortion increases linearly with temperature at a rate of ~13 K/GPa above 0.89 GPa.