Direct evidence of Ni magnetic moment in TbNi2Mn—X-ray magnetic circular dichroism

Abstract We have investigated the individual magnetic moments of Ni, Mn and Tb atoms in the intermetallic compound TbNi 2 Mn in the Laves phase (magnetic phase transition temperature T C ~131 K) by X-ray magnetic circular dichroism (XMCD) studies at 300 K, 80 K and 20 K. Analyses of the experimental results reveal that Ni atoms at 20 K in an applied magnetic field of 1 T carry an intrinsic magnetic moment of spin and orbital magnetic moment contributions 0.53±0.01 μ B and 0.05±0.01 μ B , respectively. These moment values are similar to those of the maximum saturated moment of Ni element. A very small magnetic moment of order B has been measured for Mn. This suggests that Mn is antiferromagnetically ordered across the two nearly equally occupied sites of 16d and 8a. A magnetic moment of up to ~0.3 μ B has been observed for the Tb atoms. Identification of a magnetic moment on the Ni atoms has provided further evidence for the mechanism of enhancement of the magnetic phase transition temperature in TbNi 2 Mn compared with TbNi 2 ( T C ~37.5 K) and TbMn 2 ( T C ~54 K) due to rare earth–transition metal (R–T) and transition metal–transition metal (T–T) interactions. The behaviour of the X-ray magnetic circular dichroism spectra of TbNi 2 Mn at 300 K, 80 K and 20 K – above and below the magnetic ordering temperature T C ~131 K – is discussed.