Novel Field-induced Magnetic Transitions of GdMn₂Ge₂

Abstract

Magnetization curves were measured for GdMn₂Ge₂ single crystals, which show a first-order magnetic transition from a ferrimagnetic state to an antiferromagnetic state at T₁=95 K. The field-induced transition from the ferrimagnetic state to a high-field state was observed for both H⊥c and H||c below T₁. The transition field, H_C, in H⊥c goes to zero with increasing temperature to T₁, while that in H||c gradually decreases without falling to zero at T₁. The results were analyzed in terms of a molecular field approximation, in which strong strain dependence of the interlayer Mn–Mn interaction was taken into consideration. The experimental data are well reproduced by the calculated results. The calculations predict that the compound undergoes double magnetic transitions in high magnetic fields for H||c just above T₁, which was confirmed by the measurements.