Combined effects of pressure and Ru substitution on BaFe2As2

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 to infer their room temperature, hydrostatic limits: 3.5 and 6.5 GPa, respectively.

Effects of isovalent substitution and pressure on the interplane resistivity of single-crystalBa(Fe1−xRux)2Tanatar1, Torikachvili2, Thaler3 et al. 2014Phys. Rev. BSelf Cite

“…It is remarkable that two different types of iso-valent substitution give rise to similar effects on both the inplane and inter-plane temperature-dependent electrical resistivity. It was shown previously that the effects of pressure and of the iso-valent Ru substitution on in-plane resistivity are very similar 27,28 . In a way, pressure provides an independent tuning parameter for quantum criticality, which has a significant advantage: it does not introduce substitutional disorder.…”

“…Importantly, Ru substitution does not lead to changes of the Fermi surface beyond the suppression of the folding effects of the magnetic wavevector 25 . Ru substitution was also shown to act similar to application of pressure [26][27][28] . Study of the interplane resistivity using pressure as a tuning parameter provides an additional possibility to tune system without introducing substitution disorder, inevitable for all types of dopings and particularly strong when substitutions are made in Fe site.…”

Solidification and loss of hydrostaticity in liquid media used for pressure measurements

“…7, we determined the solidification temperature in pressures up to ≈ 2.3 GPa of five other liquid PTM: 1:1 n-pentane/isoamy alcohol, 4:1 methanol/ethanol, 1:1 Fluorinert FC72/FC84, Daphne 7373, and pure isopentane. We also investigated Dow Corning PMX silicone oils of 200 and 600,000 centistoke (cst) viscosities, but were unable to unequivocally determine their freezing points.…”

Electrical resistivity study of CeZn11: Magnetic field and pressure phase diagram up to 5 GPa

“…23 In this study, we used a 1:1 mixture of n-pentane:isopentane, which is a more hydrostatic medium. 25,26 The solidification of this medium occurs at room temperature at ∼6-7 GPa. 25,27 However, this medium is more compressible and, as a result, our pressure limit was reduced to ∼5 GPa.…”

“…25,26 The solidification of this medium occurs at room temperature at ∼6-7 GPa. 25,27 However, this medium is more compressible and, as a result, our pressure limit was reduced to ∼5 GPa. In order to ensure the sealing of the pressure cell, the initial pressure has to be larger than 2 GPa.…”