Peak effect in CeRu<SUB>2</SUB>: history dependence and supercooling

We present experimental results on single crystal CeRu2 showing that the extent of 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 history effect is observed is larger if the vortex lattice is prepared by lowering T from above TC in constant H i.e. by field cooling. We compare this history effect with the very recently reported history dependence of peak-effect in detwinned single crystals of YBaCuO, highlighting the similarities and differences. We discuss the possibility of a first order vortex solid-solid transition in CeRu2 within the realm of recent theoretical developments in the field of vortex matter