Magnetic States of a Quenched Random Site Heisenberg Magnet with Competitive Exchange Interactions. I. High‐Temperature Magnetic States in Simple and Body‐Centered Cubic Lattices

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Abstract
For a quenched random site Heisenberg system with competitive nearest‐neighbour exchange interactions (IAA > 0, IAB ≶0, and IBB < 0) the molecular field distribution functions of various random magnetic structures are derived in the approximation of large nearest‐neighbour number z (z >> 1). The obtained distribution functions are utilized to discuss magnets with simple (s.c.) and body‐centered cubic (b.c.c.) lattices. It is shown that at high temperatures random collinear ferromagnetic and antiferromagnetic states (and a canted structure as well) can occur at the transition from the paramagnetic state. The occurrence of a spin‐glass state in s.c. and b.c.c. lattices at high temperatures is scarcely probable even in the framework of the molecular field approximation (MFA).