A study of the high temperature spin reorientation in YCoFe(3)B.

The iron-57 Mössbauer spectra of YCoFe(3)B have been measured between 4.2 and 480 K and reveal that YCoFe(3)B exhibits an axial orientation of the iron magnetic moments below 450 K and a basal orientation above 450 K. This spin reorientation, also observed in the thermomagnetic curves, results from the different signs of the contributions to the magnetic anisotropy of the 2c and 6i sites that are occupied by iron. The neutron diffraction patterns of YCoFe(3)B have been measured at 2 K and between 290 and 770 K and have been successfully analyzed with a model compatible with the magnetic orientation obtained from the Mössbauer spectra. The hybridization between the cobalt or iron 3d orbitals and the boron 2p orbitals leads to a larger magnetic moment and hyperfine field on the 2c site as compared to the 6i site.