Evidence for a smooth superconductor to normal state transition for   nonzero applied magnetic field in RbOs2O6
  The effect of the magnetic field on the critical behavior of RbOs2O6 is investigated. We present and analyze magnetization data, revealing remarkable consistency with a magnetic field induced finye size effect. It is traced back that at temperatures Tp(H) smaller than Tc the correlation length cannot grow beyond the limiting length scale set by the magnetic field. Thus, for nonzero H the transition from the superconducting to the normal state turns out to be smooth and the apropriately scaled magnetization data fall on a single curve. 
T. Schneider, R. Khasanov, J. Karpinski, S. M. Kazakov and H. Keller