Multiple magnetic ordering phenomena evaluated by heat capacity measurements inEr1−xTbxAl2Laves-phase alloys

Abstract

Heat capacity measurements in zero and applied magnetic fields have been performed on a series of ${\text{Er}}_{1\ensuremath{-}x}{\text{Tb}}_{x}{\text{Al}}_{2}$ 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 ${\text{Er}}_{1\ensuremath{-}x}{\text{Pr}}_{x}$ and ${\text{Er}}_{1\ensuremath{-}x}{\text{Dy}}_{x}{\text{Al}}_{2}$ 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 magnetoelastic, crystalline electric field, and quadrupolar effects. This competition gives rise to the observed multiple magnetic ordering transitions in ${\text{Er}}_{1\ensuremath{-}x}{\text{Pr}}_{x}$ and ${\text{Er}}_{1\ensuremath{-}x}{\text{Dy}}_{x}{\text{Al}}_{2}$ alloys. Tb and Er also have opposite signs of second-order Steven's factors, and therefore the observed anomalies in the ${\text{Er}}_{1\ensuremath{-}x}{\text{Tb}}_{x}{\text{Al}}_{2}$ alloys may also be interpreted in terms of competing quadrupolar, magnetoelastic, and crystalline electric field effects. The magnetocaloric properties of the ${\text{Er}}_{1\ensuremath{-}x}{\text{Tb}}_{x}{\text{Al}}_{2}$ alloy system have also been evaluated.