Electronic and magnetic properties of ErxY1-xCo₂compounds

Ferromagnetic compounds of the series Er x Y 1-x Co 2 (x=1, 0.8, 0.7, 0.6) have been investigated in specific-heat, thermal-expansion, magnetisation, AC susceptibility and resistivity experiments. The magnetic moment on the Co atoms decreases with decreasing Er content, as does the Curie temperature. The character of the magnetic transition changes from first order to second order around x=0.7. This change is compared with the similar one observed in other RE x Y 1-x CO 2 compounds with RE-Gd, Tb, Dy and is discussed in terms of the Inoue-Shimizu model by taking into account the strong temperature dependence of the magnetic susceptibility of the 3d electrons. The spontaneous volume magnetostriction at zero temperature, the magnetic contribution to the specific heat and the magnetic entropy below the magnetic ordering temperature are determined. The experimental results for these quantities confirm the induced character of the cobalt magnetic moment in these compounds.