First order magneto-structural phase transition in various functional materials

Abstract

First order magneto-structural transition plays an important role in the functionality of various magnetic materials of current interest. Rare-earth manganese oxide systems showing colossal magnetoresistance and Gd₅ (Ge,Si)₄ alloys showing giant magnetocaloric effect are typical examples of such functional materials. The key features of this magneto-structural transition in these two quite distinct types of materials are phase-coexistence and metastability. We highlight this generality by comparing the experimental results with those obtained in another class of magnetic materials. A generalized framework of disorder broadened first order phase transition is introduced to understand the interesting experimental results which have some bearing on the functionality of the concerned materials.