Spin reorientation transitions in Ho1-xDyxAl2 alloys

HoAl2 undergoes a first order spin reorientation transition at 20 K, which is accompanied by a sharp peak in the heat capacity data. Here, we have explored the effect of Dy doping on the spin reorientation transitions in Ho1-xDyxAl2 alloys by heat capacity measurements. The first order spin reorientation transition in HoAl2 changes to a second order transition as Ho is partially replaced by Dy in Ho1-xDyxAl2. The Curie temperature shifts to higher temperatures while the spin reorientation transition shifts to lower temperatures with increasing Dy concentration. The observations are interpreted by taking into consideration the higher order Stevens factors that significantly contribute to the free energy of the system. The magnetocaloric properties of the Ho1-xDyxAl2 alloys have also been calculated.