Search and identification of repeated magnetic compensation in Nd_1-xR_xAl₂ (R = Gd, Tb) series

Abstract

We undertook investigations in polycrystalline R_xR'_1-xAl₂ alloys, in particular, explored the stoichiometries, Nd_0.8Gd_0.2Al₂ and Nd_0.8Tb_0.2Al₂, to study the magnetic compensation behavior in them in the context of contemporary interest. In these admixed rare-earth (RE) intermetallics, the compensation phenomenon is characterized by a crossover of the M = 0 axis in the low field thermomagnetic response, and a turnaround behavior due to the field-induced reversal in the orientations of the RE moments at high fields. While the characteristic attributes are present in Nd_0.8Gd_0.2)Al₂, a repeated/multiple magnetic compensation behavior stands observed in Nd_0.8Tb_0.2Al₂. The ac susceptibility, the heat capacity and the transport measurements in the latter compound reveal the onset of two quasi-antiferromagnetic transitions one after the other on cooling down from the high temperature end. The two magnetic transitions involving competition between the contributions from nearly balanced weighted averages of moments of Nd³⁺ and Tb³⁺ ions generate the curious multiple crossings of the M = 0 axis. The results are compared and contrasted with repeated compensation behavior reported earlier in admixed Nd_0.8Gd_0.2Rh₃B₂ alloy.