MAGNETIC-PROPERTIES OF HALF-METALLIC F-ELECTRON SYSTEMS

A microscopic model is proposed to describe magnetic properties of half-metallic f-electron systems. We explicitly take into account the energy gap in the conduction band and the intra-atomic exchange interaction between localized f-electrons and conduction electrons. Based on the model Hamiltonian, the temperature dependence of the magnetic properties are studied assuming the ferromagnetic ground state. The relative stability of ferromagnetic state against antiferromagnetic state is also discussed by perturbation expansion in terms of the hybridization between the conduction and the localized f-electron states. Some implications are given for UNiSn, which shows the transition from paramagnetic semiconductor to antiferromagnetic metal by lowering temperature.