Pressure Effects on Superconducting Quasiskutterudite Sr3Rh4Sn13 Compared to the Ambient Pressure Properties of Ca3Rh4Sn13 and La3Rh4Sn13 Compounds

Herein, the transport properties of Sr3Rh4Sn13, Ca3Rh4Sn13, and La3Rh4Sn13 quasi-skutterudites are studied which show sharp superconducting (SC) transition with a transition temperature, T-c, approximate to 4.7, approximate to 8, and approximate to 2 K, respectively. In Sr3Rh4Sn13 system, electrical resistivity data evidence a pronounced anomaly before the SC transition at T* approximate to 136 K. No such anomalies are observed in the other two systems. Detailed structural investigations using synchrotron single-crystal and powder diffraction reveal that these systems have cubic structure with Sr3Rh4Sn13 and Ca3Rh4Sn13 being in PmPm3 over bar $\overset{\cdot}{3}$n space group setting. The La3Rh4Sn13 shows additional weak reflections which can be described by I4132 space group with almost doubled lattice parameters compared to Sr3Rh4Sn13 system. All three systems are found to show weak Raman modes below 240 cm(-1). High-pressure (HP) resistivity measurements up to 3.2-GPa on Sr3Rh4Sn13 system reveal that the T* anomaly decreases almost linearly with pressure whereas the superconducting T-c almost linearly increases. HP structural investigations on Sr3Rh4Sn13 compound reveal that the structure remains in the cubic Pm3 over bar $\overset{\cdot}{3}$n phase in 0-10 GPa range, following well a second-order Birch-Murnaghan equation of state. The results provide interesting similarities and differences in the chemical and physical pressure effects on the quasi-skutterudite X3Rh4Sn13 (x = Sr, Ca, and La) system.

Automated summary

In this study, the transport properties of Sr3Rh4Sn13, Ca3Rh4Sn13, and La3Rh4Sn13 quasi-skutterudites were investigated. The Sr3Rh4Sn13 system showed a pronounced anomaly in electrical resistivity at T* approximately 136 K, while no such anomaly was observed in the other two systems. Structural investigations revealed that all three systems have a cubic structure, with La3Rh4Sn13 showing additional weak reflections. High-pressure measurements on the Sr3Rh4Sn13 system showed a linear decrease of the T* anomaly with pressure and a linear increase of superconducting Tc. The results provide interesting insights into the pressure effects on the quasi-skutterudite X3Rh4Sn13 system.