MAGNETIC-FIELD EFFECT ON FERROELASTIC AND FERROELECTRIC PROPERTIES OFRARE-EARTH MOLYBDATES

A thermodynamic description of the influence of the magnetic field on ferroelastic and ferroelectric properties of rare-earth molybdates wit h the field orientation along and perpendicular to spontaneous polariz ation is proposed. In the case of the perpendicular orientation, of th e field, the description agrees with the experimentally observed chang es in the electric polarization and deformation in terbium molybdate. Different types of dependences of deformation, electric polarization, and magnetic moment on the magnetic field parallel to spontaneous pola rization are obtained, and the phase transition of the First kind due to the magnetic field induced by magnetoelectric interaction is predic ted in ferroelastic, ferroelectric, and magnetic subsystems. The expre ssion Is found for the shift of the transition temperature in the magn etic field.