IRREVERSIBLE ALTERATIONS OF FERROELECTRIC DOMAIN-STRUCTURE IN PARAMAGNETIC RARE-EARTH MOLYBDATES INDUCED BY A MAGNETIC-FIELD

The effect of a magnetic field on the ferroelectric domain structure o f single crystal samples of the metastable orthorhombic ferroelectric ferroelastic beta'-phase Of Sm2(MoO4)3, Gd2(MoO4)3, Tb2(MoO4)3, and Tb Gd(MoO4)3 Was investigated at 78 K in pulsed magnetic fields up to 100 kOe. It was shown that a magnetic field of certain orientation may ch ange a ferroelectric domain structure in Tb2(MoO4)3 and TbGd(MoO4)3 th at was accompanied by large changes of the electric polarization of th e sample under investigation. The effect is explained by large magneto strictive deformations. The prediction is made that there must be a po sitive longitudinal magnetostriction in a magnetic field applied along the [100] crystallographic axis and a negative transverse magnetostri ction in the (001) plane in a magnetic field applied along the [100] c rystallographic axis in Tb2(MoO4)3 and in TbGd(MoO4)3 beta'-phases at 78 K and at a magnetic field strength of about 100 kOe.