Theory of magnetic properties of actinide compounds. II

Abstract

The electron-delocalization model of metallic actinide compounds proposed earlier by the present authors is used to interpret additional experimental data concerning the first-order magnetic-phase transitions of these materials. The model is shown to provide a quantitative explanation of the experimental sublattice magnetization, magnetic-phase change, and powder susceptibility of UAs as functions of temperature $T$. Predictions are made for the low-temperature electronic specific heat and the heats of transition of this compound. The complicated magnetic transitions observed to result from varying $x$ and $T$ in the solid solutions $\mathrm{U}{\mathrm{As}}_{1-x}{\mathrm{P}}_x$, $\mathrm{U}{\mathrm{P}}_{1-x}{\mathrm{S}}_x$, and $\mathrm{U}{\mathrm{As}}_{1-x}{\mathrm{S}}_x$ are also theoretically explained. The dependence of the magnetic exchange interactions on the conduction-band occupation is deduced from the experimental data. The agreement between theory and experiment herein reported provides additional confirmation of the present theoretical model.