Combined effects of pressure and Ru substitution on BaFe2As2

TL;DR

This study investigates how pressure and Ru substitution jointly influence the phase diagram and superconductivity in BaFe2As2, revealing that 3 GPa pressure is roughly equivalent to 10% Ru substitution and highlighting media sensitivity in resistivity measurements.

Contribution

It provides a detailed comparison of pressure and Ru substitution effects on BaFe2As2, establishing their equivalence and analyzing media sensitivity in high-pressure resistivity experiments.

Findings

3 GPa pressure roughly equals 10% Ru substitution in effects.

Superconductivity emerges as magnetic order is suppressed by pressure and Ru.

Liquid media melting affects resistivity measurements and hydrostatic limits.

Abstract

The ab-plane resistivity of Ba(Fe1-xRux)2As2 (x = 0.00, 0.09, 0.16, 0.21, and 0.28) was studied under nearly hydrostatic pressures, up to 7.4 GPa, in order to explore the T-P phase diagram and to compare the combined effects of iso-electronic Ru substitution and pressure. The parent compound BaFe2As2 exhibits a structural/magnetic phase transition near 134 K. At ambient pressure, progressively increasing Ru concentration suppresses this phase transition to lower temperatures at the approximate rate of ~5 K/% Ru and is correlated with the emergence of superconductivity. By applying pressure to this system, a similar behavior is seen for each concentration: the structural/magnetic phase transition is further suppressed and superconductivity induced and ultimately, for larger x Ru and P, suppressed. A detailed comparison of the T-P phase diagrams for all Ru concentrations shows that 3 GPa of pressure is roughly equivalent to 10% Ru substitution. Furthermore, due to the sensitivity of Ba(Fe1-xRux)2As2 to pressure conditions, the melting of the liquid media, 4 : 6 light mineral oil : n-pentane and 1 : 1 iso-pentane : n-pentane, used in this study could be readily seen in the resistivity measurements. This feature was used to determine the freezing curves for these media and infer their room temperature, hydrostatic limits: 3.5 and 6.5 GPa, respectively.