Transition from the antiferromagnetic to a nonmagnetic state in FeBO3 under high pressure

A (FeBO3)-Fe-57 single crystal is studied by the nuclear forward scattering (NFS) method. The NFS time spectra from Fe-57 nuclei are recorded at room temperature under high pressures up to 50 GPa in a diamond anvil cell. In t he pressure interval 0 < p < 44 GPa, the magnetic field H-Fe at the Fe-57 n uclei is found to increase nonlinearly, reaching a maximum value of 48.1 T at p = 44 GPa. As the pressure increases further and reaches the point p = 46 GPa, the field H-Fe abruptly drops to zero, indicating that a transition from the antiferromagnetic to a nonmagnetic state occurs in the crystal. I n the pressure interval 0 < p < 46 GPa, the magnetic moments of the iron io ns lie in the (111) basal plane of the crystal. Several possible mechanisms of magnetic collapse are discussed. (C) 2001 MAIK "Nauka/Interperiodica".