Anomalous Peak Effect in CeRu2 and NbSe2 : Fracturing of a Flux Line Lattice?

CeRu2 and 2H-NbSe2 display remarkable similarities in their magnetic response, reflecting the manner in which the weakly pinned flux line lattice (FLL) loses spatial order in the Peak Effect (PE) regime. The discontinuous change in screening response near the onset of PE and the history dependence in it are attributed to a disorder-induced fracturing transition of the FLL, as an alternative to the scenario involving the appearance of a spatial modulation in superconducting order parameter in CeRu2.