Density of states and magnetic properties of the rare-earth compounds RFe2, RCO2 and RNi2

2014 The density of states of yttrium compounds YM2 (M = Fe, Co, Ni) is calculated within a tightbinding scheme. Using the Stoner model, conclusions are drawn about their magnetic and electronic properties. In YCo2, we show that one has to introduce paramagnon effects in order to explain the electronic properties. The additional d-f interaction introduced by rare-earth atoms (R) in RM2 is treated with a Hartree-Fock approximation. Little change is obtained in iron and nickel compounds. Conversely, in RCo2 compounds, the exchange field due to the rare-earth atoms can produce collective metamagnetism as described by Wohlfarth and Rhodes [1] and cobalt becomes magnetic. This effect stems from the position of the Fermi level of these compounds in a steep decrease of the density of states. Curie temperature, order of the transition and effect of an external magnetic field are studied following this method. Other consequences are drawn from the model. LE JOURNAL DE PHYSIQUE TOME 40, AOÛT 1979, Classification Physics Abstracts 75.10L201371.25P