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

Abstract

Herein, the transport properties of Sr3Rh4Sn13, Ca3Rh4Sn13, and La3Rh4Sn13 quasi‐skutterudites are studied which show sharp superconducting (SC) transition with a transition temperature, Tc, ≈4.7, ≈8, and ≈2 K, respectively. In Sr3Rh4Sn13 system, electrical resistivity data evidence a pronounced anomaly before the SC transition at T* ≈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 PmPmn 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 Tc almost linearly increases. HP structural investigations on Sr3Rh4Sn13 compound reveal that the structure remains in the cubic Pmn 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.