Magnetic and Thermomagnetic Properties of Materials Based on R(Co1 – xFex )2 Laves Phases with Heavy Rare-Earth Metals

Resumo

The crystal structure, the temperature and field dependences of the magnetization M and of the magnetic contribution into the entropy ΔS_m, the temperature dependences of the high-field susceptibility χ and the heat capacity C_p of specimens of polycrystal R(Co_{1 – x} Fe_x)₂ compounds, where R is Gd, Dy, Ho or Er, are studied. The width of the ΔS_m peak at half-height of its maximum (ΔT_FWHM) is estimated. The dependences of ΔT_FWHM and of the temperature behavior of ΔS_m of the specimens on the magnetic field, on the iron content (x ) and on the atomic number of the element R are determined. The causes of the broadening of the ΔS_m (T ) peak upon substitution of cobalt with iron in the R(Co_{1 – x} Fe_x)₂ compounds are considered.