Magnetism in iron around the Curie temperature: recursion calculations on regular spin configuration, with a full SPD Hamiltonian

Abstract

Previous numerical investigations of the degree and nature of short-range order around the Curie temperature, TC, in Fe using spin spirals and other regular configurations have been limited almost exclusively to d-band-only models. The authors report on calculations that fully include SPD hybridisation which is known to be important in itinerant systems. The local moments and total energies which they obtain are rather different from the previous results and substantiate a recent hypothesis of Heine and Joynt (1988) who suggested coarse-grained disordering on the scale of the Stoner wavevector. It is found that to a first approximation Fe behaves like a Heisenberg ferromagnet but the corrections obtained from different configurations have contradictory implications. This suggests the existence of multi-atom forces. The authors obtained a value for the spin wave stiffness in excellent agreement with experiment and comment on the implications of the results for models of the disordering of Fe around TC.