Overview No. 145 Metamagnetic transitions, phase coexistence and metastability in functional magnetic materials

Magnetic field-induced transitions (metamagnetic transitions) play an important role in defining functionality of various classes of magnetic materials. Rare earth manganites showing colossal magnetoresistance and Gd5(Ge1−xSix)4 alloys showing a giant magnetocaloric effect are typical examples that are of interest to the solid-state physics, chemistry and materials science communities. The key features of the metamagnetic transitions occurring in these systems are phase coexistence and metastability. This generality is highlighted by comparing experimental results characterizing three different classes of magnetic materials. A generalized framework of disorder-influenced first-order phase transition is introduced to understand the experimental data, which have considerable bearing on the functionality of these model materials.