Finite-temperature magnetism of disordered Fe-V alloys

The finite-temperature magnetism of disordered Fe-V alloys changes continuously from the local-moment type to the itinerant type as a function of composition. This is investigated using the finite-temperature theory of the local-environment effect (LEE) by means of the functional-integral method. The magnetization, local-moment distributions, Curie temperature, high-field susceptibility, paramagnetic susceptibility, and the internal-field distribution with respect to ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ are calculated as functions of concentration and temperature. Although the magnetization decreases monotonically with increasing V concentration, the Curie temperature shows a maximum. This is shown to be due to both the itinerant character and the alloying effect. The strong LEE on the amplitude of local moments explains the observed broad internal-field distributions. Induced and local-moment types of Fe coexist in the concentrated alloys because of the LEE. A rapid increase of the effective Bohr magneton number in the paramagnetic susceptibility is found near the critical concentration at which ferromagnetism disappears. The validity of the theory is also examined by comparing the present results with those of cluster coherent-potential-approximation calculations at low temperatures.