FIRST-ORDER MAGNETIC PHASE TRANSITIONS AND COLOSSAL MAGNETORESISTANCE: JOINING MANGANESE PEROVSKITES AND MnAs

Abstract

We revise some recent results on the nature of the magnetic phase transition of ferromagnetic manganese perovskites with colossal magnetoresistance. It is found that they exhibit first-order magnetic phase transitions mainly due to strong lattice effects. The presence of such first-order transition is strongly linked to the existence of a temperature region above the Curie Temperature with a phase-separated regime of coexisting metallic and insulating clusters. This situation is compared with that of MnAs , paradigm of system with first-order magnetic phase transition, and we observe a parallel phenomenology of these apparently different systems. This serves as a clue for the finding of a phase-separated regime also in MnAs and, moreover, for the finding of a colossal magnetoresistive effect similar to that of manganese perovskites.