PUB - Publikationen an der Universität Bielefeld

We report on broadband and in-plane angle dependent ferromagnetic resonance measurements of MnN (30 nm)/CoFeB (t(CoFeB)) exchange bias bilayer systems with CoFeB thicknesses ranging from 5 to 20 nm. We find that the strong unidirectional anisotropy in this system is accompanied by a strong uniaxial in-plane anisotropy and a small interfacial perpendicular anisotropy (K-perpendicular to,K- i = 0.043 +/- 0.001 erg/cm(2)). The strength of the interfacial exchange bias coupling in this system Delta sigma(eb) = 0.193 +/- 0.005 erg/cm(2) is only 2.5 times larger than the interfacial uniaxial coupling strength Delta sigma(u) = 0.076 +/- 0.003 erg/cm(2). The relaxation in this system also shows a strong unidirectional and uniaxial in-plane anisotropy. While the observed thickness dependence of the uniaxial anisotropy of the relaxation is consistent with an interfacial two-magnon scattering contribution, we find that this is not the case for the unidirectional relaxation.