Multiple magnetic ordering phenomena evaluated by heat capacity measurements in Er_(1-x)Tb_xAl_2 Laves-phase alloys

摘要

Heat capacity measurements in zero and applied magnetic fields have been performed on a series of Er_(1-x)Tb_x-Al_2 pseudobinary Laves-phase alloys. Different anomalies that change with Tb concentrations have been observed. These anomalies represent multiple magnetic ordering phenomena, similar to those reported in Er_(1-x)Pr_x and Er_(1-x)Dy_xAl_2 alloys. In common, all alloys contain mixtures of lanthanide metals with opposite signs of the second-order Steven's operators, which were believed to cause competition between the magne-toelastic, crystalline electric field, and quadrupolar effects. This competition gives rise to the observed multiple magnetic ordering transitions in Er_(1-x)Pr_x and Er_(1-x)Dy_xAl_2 alloys. Tb and Er also have opposite signs of second-order Steven's factors, and therefore the observed anomalies in the Er_(1-x)Tb_xAl_2 alloys may also be interpreted in terms of competing quadrupolar, magnetoelastic, and crystalline electric field effects. The mag-netocaloric properties of the Er_(1-x_Tb_xAl_2 alloy system have also been evaluated.