Magnetic moment arrangement in amorphous FeErB

Magnetization measurements and Mössbauer spectroscopy with and without a monochromatic circularly polarized Mössbauer source (MCPMS) have been performed in order to determine the magnetic properties of the amorphous alloy Fe0.66Er0.19B0.15. The system is found to order ferrimagnetically at TC=330K and to show a compensation temperature (Tcomp) at 120K. A reorientation of the magnetic moments of iron and erbium during sample cooling through the compensation point in magnetic field is clearly displayed in the MCPMS data. The orientation of the net magnetic moment is due to the orientation of Fe moments above Tcomp and to Er moments at low temperatures. The results are compatible with a model of predominantly antiferromagnetic Fe–Er coupling accompanied by random local anisotropy acting on the Er moments.