DIPOLE-DIPOLE INTERACTION AND MAGNETIC-OR DERING IN KER(MOO4)2 .2. PHASE-TRANSITIONS IN KER(MOO4)2 INDUCED BY EXTERNAL MAGNETIC-FIELD

Using the model of magnetic structure of KEr(MoO4)2 derived in [1] in the approximation of magnetic with purely dipole-dipole spin-spin inte ractions and equivalent RE sites in the cell, the phase transitions in duced in the system by magnetic field H parallel-to a and H parallel-t o c are considered. It is shown that the magnetic nonequivalence of th e ions of neighbouring chains not coupled by the center of inversion r esults in a four-sublattice magnetic structure responsible for a metam agnetic phase transition at H parallel-to a. The angular dependence of the EPR spectrum is analysed. The angles of rotation of the crystal f ield local axes for nonequivalent centers and the residual exchange in teraction are estimated. From the investigations and the estimations i t is concluded that the dipole-dipole interactions are dominant in the formation of the magnetic properties of the compound.