In-plane reorientation of magnetization in epitaxial exchange biased Fe/MnPd bilayers

We investigated the in-plane reorientation of magnetization in epitaxial Fe/MnPd bilayers. The samples with various thicknesses of MnPd and Fe layers present a conventional square and an unusual two-step exchange biased hysteresis loops at different temperature. The shape of the loops is reproduced using the coherent rotation model and including the relative orientation of the uniaxial anisotropy with respect to the exchange bias. The parallel and perpendicular uniaxial anisotropies in the ferromagnetic layer are linked to the aligned and the reoriented states, respectively. The magnetic reorientation between the aligned and the reoriented states, which is determined by the competition between the interface exchange coupling and the intrinsic uniaxial energies, is shown to be driven by the temperature, as well as the thickness of MnPd and Fe layers.