EPR study of the ground state of Mn super(2+) impurity ions in alumoborates MAl sub(3)(BO sub(3)) sub(4 ) (M = Y, Eu, Tm)

New data about the ground state of the Mn super(2+) impurity ions in a series of single crystals of alumbrados MAl sub(3)(B0 sub(3)) sub(4 ), where M = Y, Eu, Tm were obtained. The electron paramagnetic resonance (EPR) spectra of the Mn super(2+) spectra were studied, the parameters of the spin Hamiltonian describing the angular dependence of the spectrum were defined. It was shown that Mn super(2+) ions substitute trivalent ions of rare earth metals without changing the symmetry of the substitution site. The charge compensation process was found to be a nonlocal one. The cooling of the crystals leads to the increase of the splitting of the ground state, which is associated with the anisotropy of the thermal expansion coefficient. It was shown that an application of the superposition model to explain the distortions induced by an impurity Mn super(2+) ion has some limitations. The EPR linewidth of the Mn super(2+) ion in the TmAl sub(3)(BO sub(3)) sub( 4) crystal increases with increasing temperature as a result of the dipole-dipole and exchange interactions with the excited states of the host lattice Tm super(3+) ion.