Pressure Induced Superconductivity and Structural Transitions in Ba(Fe0.9Ru0.1)2As2

TL;DR

This study investigates how applying high pressure induces superconductivity and structural phase transitions in ruthenium-doped BaFe2As2, revealing a maximum Tc around 5.5 GPa and a transition to a collapsed tetragonal phase at higher pressures.

Contribution

It provides the first detailed high-pressure measurements of superconductivity and structural changes in Ru-doped BaFe2As2, highlighting pressure effects on its phase diagram.

Findings

Superconductivity appears at 3.9 GPa with Tc ~24 K.

Maximum Tc occurs near 5.5 GPa, then decreases with pressure.

A tetragonal to collapsed tetragonal phase transition occurs at 14 GPa.

Abstract

High pressure electrical resistance and x-ray diffraction measurements have been performed on ruthenium-doped Ba(Fe0.9Ru0.1)2As2, up to pressures of 32 GPa and down to temperatures of 10 K, using designer diamond anvils under quasi-hydrostatic conditions. At 3.9 GPa, there is an evidence of pressure-induced superconductivity with Tc onset of 24 K and zero resistance at Tc zero of ~14.5 K. The superconducting transition temperature reaches maximum at ~5.5 GPa and then decreases gradually with increase in pressure before completely disappearing above 11.5 GPa. Upon increasing pressure at 200 K, an isostructural phase transition from a tetragonal (I4/mmm) phase to a collapsed tetragonal phase is observed at 14 GPa and the collapsed phase persists up to at least 30 GPa. The changes in the unit cell dimensions are highly anisotropic across the phase transition and are qualitatively similar to those observed in undoped BaFe2As2 parent.