Structure and Magnetic Phase Diagrams of Multiferroic Mn₂GeO₄

Abstract

Crystallographic structure and magnetic phase diagrams were investigated for single crystals of multiferroic Mn 2 GeO 4 showing successive magnetic transitions at T N1 = 47 K, T N2 = 17 K, and T N3 = 5.5 K. Substantial anomalies of lattice distortion were observed at the respective magnetic transition temperatures. We also found that the phase boundary at T N2 remarkably shifts by applying a magnetic field H and strongly depends on the direction of H . Possible origins of the observed phenomena are discussed from the perspective of magnetic interactions and relevant magnetostriction in Mn 2 GeO 4 with the olivine structure.