Unexpectedly wide reversible vortex region in beta-pyrochlore RbOs2O6

P. LEGENDRE; YANINA FASANO; I. MAGGIO-APRILE; /O. FISCHER; ZBIGNIEW BUKOWSKI; SERGIY KATRYCH; JANUSZ KARPINSKI

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Año: 2008 vol. 78 p. 144513 - 144519

0163-1829

We study the extent of the reversible region in the vortex phase diagram of recently available RbOs2O6 single crystals [1] 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 conventional since we estimate a Ginzburg number Gi = 5 10^7. On the contrary, the relevance of quenched disorder is unconventionally small providing the critical-current density ratio at low fields and temperatures is of the order of that found in high-Tc´s. Therefore, an intrinsically low magnitude of bulk pinning promotes the uncommonly wide reversible vortex region that seems to be generic to beta-pyrochlores.2O6 single crystals [1] 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 conventional since we estimate a Ginzburg number Gi = 5 10^7. On the contrary, the relevance of quenched disorder is unconventionally small providing the critical-current density ratio at low fields and temperatures is of the order of that found in high-Tc´s. Therefore, an intrinsically low magnitude of bulk pinning promotes the uncommonly wide reversible vortex region that seems to be generic to beta-pyrochlores.