Magnetic field induced phase transition in KEr(MoO4)2. Vibronic model

Abstract

A vibronic model with Kramers magnetic ions is investigated in a parameter region that does not admit phase transitions on changes of the temperature T in the absence of magnetic field H. The H–T (θ=0) and θ–H (T=const) phase diagrams (the angle θ specifies the orientation of the field relative to the symmetry axis of the crystal) are constructed in the mean field approximation. A comparison is made with the experimentally obtained phase diagrams of the KEr(MoO4)2 crystal.