Moessbauer study of spin-reoriented phase transition on surface 02 in volume of Fe3BO6

Spin-reoriented phase transition in the surface layer of Fe3BO6 macroscopic antiferromagnetic crystal with a weak ferromagnetic moment is studied. Simultaneous gamma-, X-ray and electron Moessbauer spectroscopy enabling to study both surface and volume properties of the bulk crystal is used for measurements. It is detected the following: 1) spin-reorientated transition of the first type observed within the crystal bulk is followed by a smooth reorientation of spins at the crystal surface; 2) boundaries of phase transition become wider with approximation to the crystal surface and there is no shift of the transition range centre; 3) directions of magnetic moments beyond the transition range at the surface and within the volume of the crystal vary. The obtained experimental data correlate with deductions of phenomenological theory of spin-reoriented phase transitions at macrocrystal surface