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 TbNi2Mn in the Laves phase (magnetic phase transition temperature TC ~131K) by X-ray magnetic circular dichroism (XMCD) studies at 300K, 80K and 20K. Analyses of the experimental results reveal that Ni atoms at 20K in an applied magnetic field of 1T carry an intrinsic magnetic moment of spin and orbital magnetic moment contributions 0.53±0.01μB and 0.05±0.01μB, respectively. These moment values are similar to those of the maximum saturated moment of Ni element. A very small magnetic moment of order <0.1μB 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 ~0.3μB 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 TbNi2Mn compared with TbNi2 (TC~37.5K) and TbMn2 (TC~54K) 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 TbNi2Mn at 300K, 80K and 20K – above and below the magnetic ordering temperature TC ~131K – is discussed.