We study the extent of the reversible region in the vortex phase diagram of recently available RbOs2O6 single crystals \cite{Rogacki08a} by means of bulk magnetization measurements. We found that the irreversible magnetic response sets in at a field Hirr(T)∼0.3Hc2(T) for 0.5≲T/Tc≲0.8, yielding a reversible vortex region that is uncommonly wide in comparison with typical low-Tc materials. The relevance of thermal fluctuations is limited since we estimate a Ginzburg number Gi=5×10−7. However, the relevance of quenched disorder is unconventionally low since the critical-current density ratio at low fields and temperatures is of the order of that found in high-Tc's. We therefore conclude that an intrinsically low bulk pinning magnitude favors the existence of an unexpectedly wide reversible vortex region that seems to be generic to β-pyrochlores.
Cite
@article{arxiv.0806.3346,
title = {Unexpectedly wide reversible vortex region in $\beta$-pyrochlore RbOs$_{2}$O$_{6}$},
author = {Pierre Legendre and Yanina Fasano and Ivan Maggio-Aprile and Øystein Fischer and Zbigniew Bukowski and Sergiy Katrych and Janusz Karpinski},
journal= {arXiv preprint arXiv:0806.3346},
year = {2008}
}