  Classical Heisenberg antiferromagnets with uniaxial exchange anisotropy and a
cubic anisotropy term in a field on simple cubic lattices are studied with the
help of ground state considerations and extensive Monte Carlo simulations.
Especially, we analyze the role of non-collinear structures of biconical type
occurring in addition to the well-known antiferromagnetic and spin-flop
structures. Pertinent phase diagrams are determined, and compared to previous
findings.

Statistical Mechanics