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.
@article{arxiv.0706.0439,
title = {Multiband superconductivity and penetration depth in PrOs4Sb12},
author = {D. E. MacLaughlin and Lei Shu and R. H. Heffner and J. E. Sonier and F. D. Callaghan and G. D. Morris and O. O. Bernal and W. M. Yuhasz and N. A. Frederick and M. B. Maple},
journal= {arXiv preprint arXiv:0706.0439},
year = {2009}
}