Metamagnetic and orientational transitions in TbFeO3 orthoferrite: magnetoelectric phase diagrams

Metamagnetic and orientational phase transitions in the interacting rare-earth and iron subsystems in magnetic fields up to 5 T in the ab-plane at T = 1.85 K are studied in orthoferrite TbFeO3 with magnetic moments of Ising Tb3+ ions lying in the ab-plane of the crystal. The transitions manifest themselves as anomalies (jumps) in the magnetization curves sigma(H) for a fixed field orientation or anomalies in the angular dependences of the magnetization, as well as in the field dependences of the electric polarization P-a(H). Phase diagrams are constructed, and magnetic structures are identified, two of which are magnetoelectric. A theoretical model is proposed to describe the observed phase transitions, and a quantitative description of the experimental phase diagrams is given. The characteristic features of the manifestation of magnetoelectric properties in the studied phenomena are established, in particular, a linear increase in polarization in an electric field up to 11 kV/cm, indicating a multidomain polar state in these fields and a memory effect after the electric field is turned off.