Electrical resistivity, Curie temperature and band structure of Ho(Fe _(1-x)Co _x) _2 compounds

摘要

Electrical resistivities for Ho(Fe _(1-x)Co _x) 2 C15 Laves phases were measured in a wide temperature region (13-1000K) and the residual, phonon and magnetic resistivities contributing to them were separated. Moreover, the parameters characterizing resistivity dependence on temperature and composition, including the Debye temperature, were determined. The differential of the magnetic part of electrical resistivity against temperature was used to estimate Curie temperatures. The Curie temperature changes approximately parabolically, increases with x, reaches a maximum at x=0.3 and then strongly decreases for higher x values. Some results of 3d and 4s electronic band structure, calculated using the full-potential linearized augmented plane wave (FLAPW) method, are presented. A distribution function for the densities of states is introduced, and a way of defining 3d and 4s band half-widths as well as band splitting energy is proposed. The calculated 3d and 4s band splitting energies for Fe, Co and stoichiometrically weighted transition metal M are presented. A simple statistical-type formula describing the Curie temperature of Ho(Fe _(1-x)Co _x) 2 intermetallics related to FLAPW results is proposed.