CHROMIUM-LIKE MODEL FOR AN ITINERANT ANTIFERROMAGNET

A model of an itinerant-electron antiferromagnet, based on two paramagnetic energy bands, an intraatomic electron-electron interaction, and the Hartree-Fock approximation is constructed. The paramagnetic bands (a nearly free-electron band hybridized with a tight-binding band) determine the basic structure of the antiferromagnet. These bands possess the nesting property, which is important in maintaining the stable antiferromagnetic state in chromium and other metals. In this model, only the interaction between the tight-binding part of the electron wave functions is considered, and the strength of this interaction is the only variable parameter. The model exhibits generally good agreement with the experimental properties of chromium. Properties of the antiferromagnetic states for this model include: (a) an antiferromagnetic periodicity, which is incommensurable with the lattice and varies slightly with interaction strength; (b) antiferromagnetic energy gaps in the band structure and an altered Fermi surface which leads to significant changes in galvanomagnetic and electronic properties; (c) a first-order phase transition at the Néel temperature, characterized by a linear relationship between TN and the antiferromagnetic energy gap, and a quadratic relationship between TN and the heat of transformation; (d) temperature-dependent peaks in the imaginary part of the dielectric constant at energies near the antiferromagnetic gap energies. © 1969 The American Physical Society.