Peak effect in the superconducting mixed state of bulk Mo-Re alloys: a dc magnetization study

We have observed, in our de magnetization studies, the peak effect (PE) in the superconducting mixed state of two compositions, Mo0.825Re0.175 and Mo0 .8Re0.2, of the binary alloy system Mo1-xRex. The PE occurs close to the H- c2(T) line at temperatures below T-c, similar to the well studied compound CeRu2. A detailed investigation of the various characteristics of this peak effect and a comparison with other superconductors of current interest sho w that the observed behaviour can be explained within the realm of critical state models of hard type-II superconductors. Our results show that the an omalies reported in CeRu2 and NbSe2 are not universal to materials showing a PE close to the H-c2(T) line and may, therefore, have an important bearin g on the phenomenology of type-II superconductors.