Multiband superconductivity and penetration depth in PrOs4Sb12

TL;DR

This paper investigates the superconducting gap structure of PrOs4Sb12 using different measurement techniques, revealing evidence for multiband superconductivity with distinct gap behaviors affecting penetration depth measurements.

Contribution

It proposes a multiband superconductivity model to reconcile differing penetration depth results obtained in vortex and Meissner states of PrOs4Sb12.

Findings

Vortex state measurements show activated temperature dependence.

Meissner state measurements suggest point nodes in the gap.

A multiband model explains the contrasting results.

Abstract

The effective superconducting penetration depth measured in the vortex state of PrOs4Sb12 using transverse-field muon spin rotation (TF-muSR) exhibits an activated temperature dependence at low temperatures, consistent with a nonzero gap for quasiparticle excitations. In contrast, Meissner-state radiofrequency (rf) inductive measurements of the penetration depth yield a T^2 temperature dependence, suggestive of point nodes in the gap. A scenario based on the recent discovery of extreme two-band superconductivity in PrOs4Sb12 is proposed to resolve this difference. In this picture a large difference between large- and small-gap coherence lengths renders the field distribution in the vortex state controlled mainly by supercurrents from a fully-gapped large-gap band. In zero field all bands contribute, yielding a stronger temperature dependence to the rf inductive measurements.