Reversal modes of exchange-spring magnets revealed by torque magnetometry

Abstract

Torque magnetometry measurements and related micromagnetic simulations are reported for SmCo/Fe exchange-spring films with uniaxial in-plane easy axis of magnetization. Rotating an applied magnetic field in plane, away from the easy direction, gives rise to an irreversible jump in the torque curves at a critical angle. The jump is associated with a switch in chirality of the magnetization spiral structure that develops in the magnetically soft Fe layer, pinned at the interface with the hard SmCo layer. Two reversal modes of the chirality are identified, one at low fields due to an in-plane untwisting of the spiral, and the other at high fields, due to an out-of-plane fanning of the spiral. © 2001 American Institute of Physics.