  We present magnetization data on a weakly pinned CeRu_2 single crystal
showing the existence of a stable state of the vortex lattice in the peak
effect region. The stable state is achieved by cycling the magnetic field by
small amplitude. This stable state is characterized by a unique value of
critical current density (J_c), independent of the magnetic history of the
sample. The results support the recent model proposed by Ravikumar et al
\cite{r39} on the history dependence of the J_c.

Superconductivity