Peak effect in CeRu2: History dependence and supercooling

We present experimental results on single crystal CeRu2 showing that the ex tent, of the history dependence of peak effect depends on the path followed in the space of field (H) and temperature (T). The (H,T) regime over which the history effect is observed is larger if the vortex lattice is prepared by lowering T from above Te in constant H, i.e., by field cooling. We comp are this history effect: with the very recently reported history dependence of peak effect in detwinned single crystals of YBaCuO and 2H-NbSe2, highli ghting the similarities and differences; We discuss the possibility of a fi rst-order vortex solid-solid transition in CeRu2 within the realm of recent theoretical developments in the field of vortex matter.