Temperature dependence of perpendicular magnetic anisotropy in CoFeB thin films

摘要

We study perpendicular magnetic anisotropy in thin films of Ta/Co_(20)Fe_(60)B_(20)/MgO by ferromagnetic resonance and find a linear temperature dependence for the first and second order uniaxial terms from 5 to 300 K. Our data suggest the possible hybridization of Fe-0 orbitals at the CoFeB/MgO interface for the origin of the first order anisotropy. However, we also find that non-interfacial contributions to the anisotropy are present. An easy-cone anisotropy is found for the entire temperature range in the narrow region of film thicknesses around the spin reorientation transition 1.2-1.35 nm.