New Magnetic Anisotropy

TLDR

The exchange anisotropy arises from the interaction between a ferromagnetic cobalt core and an antiferromagnetic cobaltous oxide shell in a compact of fine particles, and it manifests only below the antiferromagnetic material’s Néel temperature, essentially room temperature. The study reports a newly discovered exchange anisotropy in cobalt–cobaltous oxide composites, with an inferred exchange torque peaking at ~2 dyne‑cm/cm² at 77 K.

Abstract

A new type of magnetic anisotropy has been discovered which is best described as an exchange anisotropy. This anisotropy is the result of an interaction between an antiferromagnetic material and a ferromagnetic material. The material that exhibits this exchange anisotropy is a compact of fine particles of cobalt with a cobaltous oxide shell. The effect occurs only below the N\'eel temperature of the antiferromagnetic material, which is essentially room temperature for the cobaltous oxide. An exchange torque is inferred to exist between the metal and oxide which has a maximum value at 77\ifmmode^\circ\else\textdegree\fi{}K of \ensuremath{\sim}2 dyne-cm/${\mathrm{cm}}^{2}$ of interface.