Magnetostatic Modes in Antiferromagnets and Canted Antiferromagnets

Abstract

The resonance frequencies of the magnetostatic modes are calculated for an antiferromagnetic sphere with a dc magnetic field applied along the direction of easy magnetization. For resonance at a fixed frequency, the separations between the various modes are of order 0.2 (2H_exH_A)^½4πM/H_ex Oe. The magnetostatic modes of canted antiferromagnets of the α‐Fe₂O₃ type are also investigated. Application of the magnetostatic conditions and solution of the differential equation for the magnetic scalar potential for a spherical sample reveals separations between modes of order 0.1 (H₀+H_DM) 4πM/H_ex Oe. These modes are associated with the low‐frequency resonance near ω₁=γ[2H_exH_A′ + H₀+H_DM)]^½.