High pressure study of BaFe2As2 - role of hydrostaticity and uniaxial stress

TL;DR

This study explores how different pressure conditions, including hydrostatic and uniaxial stress, influence the electrical resistivity and phase transitions in BaFe2As2 single crystals, revealing the impact of stress anisotropy on superconductivity.

Contribution

It demonstrates how varying degrees of hydrostaticity and uniaxial stress alter the phase diagram and induce superconductivity in BaFe2As2, highlighting the importance of stress conditions.

Findings

Uniaxial stress reduces spin density wave order.

Different pressure media affect phase diagram and superconductivity.

Hydrostaticity level influences the emergence of superconductivity.

Abstract

We investigate the evolution of the electrical resistivity of BaFe2As2 single crystals with pressure. The samples used were from the same batch grown from self flux and showed properties that were highly reproducible. Samples were pressurised using three different pressure media: pentane-isopentane (in a piston cylinder cell), Daphne oil (in an alumina anvil cell) and steatite (in a Bridgman cell). Each pressure medium has its own intrinsic level of hydrostaticity, which dramatically affects the phase diagram. An increasing uniaxial pressure component in this system quickly reduces spin density wave order and favours the appearance of superconductivity, similar to what is seen in SrFe2As2.