MOSSBAUER INVESTIGATION OF THE PECULIAR MAGNETISM OF TB(MN1-XFEX)2 AT SMALL SUBSTITUTION OF FE FOR MN

Mossbauer experiments have been performed on the Tb(Mn0.96Fe0.04)2 intermetallic compound from liquid nitrogen temperature down to liquid helium temperature. Above 34 K, the obtained spectra are interpreted in a two sites model with populations in the ratio 3:1. Below 34 K, each site splits into two equally populated subsites differing from each other by the quadrupolar splitting and isomer shift. At this temperature, one observes also a rotation of the hyperfine field of the site of population 1. These data are consistent with an earlier proposal of a collinear magnetic structure at high temperature where only one Mn atom over four is magnetic, with a reorientation of the corresponding moment below 34 K as has been shown up by neutron scattering.