General alloy analogs of itinerant magnetic systems

Abstract

Magnetically disordered, strong correlated itinerant electron systems are studied within the Hubbard model. Following an “alloy analogy”, the approximated system hamiltonian contains local vectoral magnetic fields at the atomic sites, which can be oriented into all space directions. The statistical system of the localized magnetic moments (due to the fields) is treated by the aid of a generalized CPA-technique. Supposing a macroscopic magnetic structure of sublattice antiferromagnetism, the formation of incomplete antiferromagnetic ordering of the localized moments is examined. The results show, that the electron density plays an essential roll for the question, whether or not it is possible to go beyond the pure (itinerant) antiferromagnetic state. Including the results of earlier papers for homogeneous macroscopic magnetic structure, on the whole scale of electron densities it is summed up (at zero temperature), where the different states (without-, with incomplete- or with complete magnetic order) are able to exist. It is shown, for fixed density respectively, which different phases are passed through on changing the coupling constant.