Using x-ray magnetic circular dichroism we have detected the very interfacial spins that are responsible for the horizontal loop shift in three different exchange bias sandwiches, chosen because of their potential for device applications. The "pinned" uncompensated interfacial spins constitute only a fraction of a monolayer and do not rotate in an external magnetic field since they are tightly locked to the antiferromagnetic lattice. A simple extension of the Meiklejohn and Bean model is proposed to quantitatively account for the exchange bias fields in the three studied systems from the experimentally determined number of pinned moments and their sizes.

The temperature-dependent magnetic response of exchange-coupled FePt/FeRh thin films is described. The FePt forms a high magnetocrystalline anisotropy, high-coercivity ferromagnetic layer. The FeRh layer is antiferromagnetic at room temperature but, upon heating above a transition temperature, becomes ferromagnetic with a large magnetic moment and low magnetocrystalline anisotropy, forming an exchange–spring system and significantly lowering the coercive field of the composite system. This feature opens intriguing possibilities for media applications for thermally assisted magnetic recording where the ferromagnetic phase of FeRh is exploited to help write the media while the antiferromagnetic phase supports the long-time stability.

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Exchange bias measurements of ferromagnetic/antiferromagnetic (F/AF) bilayers are typically performed with the magnetization of the F layer parallel to the AF interface. We describe measurements of Co/Pt multilayers with out-of-plane magnetic easy axis that are exchange biased with CoO. Field-cooling experiments with the applied field perpendicular and parallel to the sample plane exhibit loop shifts and enhanced coercivities. Modeling and comparison to biasing of samples with planar easy axis suggests such measurements provide a way to probe the spin projections at F/AF interfaces.

We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy fields in results in a spin reorientation transition and an anisotropic ac susceptibility which is fully consistent with a simple single-domain model. The uniaxial and biaxial anisotropy constants vary, respectively, as the square and fourth power of the spontaneous magnetization across the whole temperature range up to . The weakening of the anisotropy at the transition may be of technological importance for applications involving thermally assisted magnetization switching.