Domain Structure of Uniaxial Antiferromagnets. The Problem of Nucleation

Abstract The dependence of the energy γ 180 and the halfwidth δ 180 of 180° L‐domain walls in antiferromagnets on the magnetic field H is calculated for low fields. At H → H 0 ( H 0 is the critical field of the spin‐flop transition) the walls expand and their energy γ180 decreases. In the spin‐flop region 90° domain structure appears. γ90 and δ 90 are determined by the value of fourth‐order anisotropy constant K 2 . The calculation of the metastable state ( K 2 <0) region shows that its boundaries may be approximated by the astroid at | K 2 | ≪ K 1 only. The wall displacement in the spin‐flop region ( K 2 ≪ 0) and the domain structure at K 2 > 0 are discussed. The problem of the new magnetic phase nucleation is considered.

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