Evidence from neutron diffraction for superconductivity in the stabilized tetragonal phase of CaFe2As2 under uniaxial pressure

TL;DR

This study uses neutron diffraction to demonstrate that the stabilized tetragonal phase of CaFe2As2 under uniaxial pressure correlates with the emergence of superconductivity below 10 K.

Contribution

It provides direct structural evidence linking the tetragonal phase stabilization to superconductivity in CaFe2As2 under uniaxial pressure.

Findings

Tetragonal phase stabilized at low temperatures above 0.06 GPa

Maximum tetragonal phase fraction coincides with superconductivity onset

Superconductivity observed below 10 K under uniaxial pressure

Abstract

CaFe2As2 single crystals under uniaxial pressure applied along the c axis exhibit the coexistence of several structural phases at low temperatures. We show that the room-temperature tetragonal phase is stabilized at low temperatures for pressures above 0.06 GPa, and its weight fraction attains a maximum in the region where superconductivity is observed under applied uniaxial pressure. Simultaneous resistivity measurements strongly suggest that this phase is responsible for the superconductivity in CaFe2As2 found below 10 K in samples subjected to nonhydrostatic pressure conditions.