Comment on "Pronounced Enhancement of the Lower Critical Field and Critical Current Deep in the Superconducting State of PrOs4Sb12"

TL;DR

This study uses muon spin rotation to investigate the superconducting properties of PrOs4Sb12 near a suspected phase transition, finding no anomalies in penetration depth that challenge previous claims of a phase transition at Tc3.

Contribution

It provides high-precision measurements of penetration depth in PrOs4Sb12, questioning earlier evidence of a phase transition at Tc3.

Findings

No anomaly in penetration depth near Tc3

Challenges previous claims of a phase transition

Supports the absence of a phase transition at Tc3

Abstract

Cichorek et al. [Phys. Rev. Lett. 94, 107002 (2005)] reported enhancements of the lower critical field Hc1(T) and critical current in superconducting PrOs4Sb12 below a transition temperature Tc3 ~ 0.6 K, and speculated that this reflects a transition between superconducting phases. Features have been observed near Tc3 in other properties, but not in the specific heat. We report muon spin rotation measurements of the penetration depth in the vortex state of PrOs4Sb12 near Hc1(T), that to high accuracy exhibit no anomaly Tc3 and therefore cast doubt on the putative phase transition.