Anomalous Compressibility Effects and Superconductivity in EuFe2As2 under High Pressures

TL;DR

This study investigates how EuFe2As2's crystal structure and electrical resistance change under high pressures up to 70 GPa, revealing anomalous compressibility effects linked to superconductivity with Tc reaching 41 K.

Contribution

It provides detailed high-pressure structural and superconducting data for EuFe2As2, highlighting anomalous compressibility effects and their correlation with superconductivity.

Findings

Anomalous lattice compression peaks at 8 GPa

Superconducting transition temperature reaches 41 K

Structural behavior normalizes above 10 GPa

Abstract

The crystal structure and electrical resistance of the structurally-layered EuFe2As2 have been studied up to 70 GPa and down to temperature of 10 K, using a synchrotron x-ray source and the designer diamond anvils. The room-temperature compression of the tetragonal phase of EuFe2As2 (I4/mmm) results in an increase in the a-axis and a rapid decrease in c-axis with increasing pressure. This anomalous compression reaches a maximum at 8 GPa and the tetragonal lattice behaves normal above 10 GPa with a nearly constant c/a axial ratio. The rapid rise in superconducting transition temperature (Tc) to 41 K with increasing pressure is correlated to this anomalous compression and a decrease in Tc is observed above 10 GPa. We present P-V data or equation of state of EuFe2As2 in both the ambient tetragonal phase and the high pressure collapsed tetragonal phase to 70 GPa.