Lorentz electron microscopy study of magnetisation reversal mechanism in exchange-coupled bilayers

摘要

The magnetisation reversal of the ferromagnetic layer in IrMn/CoFe exchange-coupled films has been investigated using Lorentz microscopy with an in-situ magnetic field applied along the unidirectional easy axis. The asymmetry of the reversal mechanism, a coercivity enhancement, and their dependence on antiferromagnetic layer thickness, have been explained by the existence of pinning sites and thermal activation in the antiferromagnetic layer.