Gyromagnetic ratio of oriented hcp Co1−x Ir x soft magnetic films

Abstract

The gyromagnetic ratio γ is a key quantity that determines spin and magnetic properties. In this study, γ is investigated via the electric detection of ferromagnetic resonance and first-principles calculations for c-axis oriented hcp-Co1−x Ir x () soft magnetic films with easy-plane magnetocrystalline anisotropy. γ increases linearly from 19.13 GHz kOe−1 for pure Co film to 19.32 GHz kOe−1 at x= 0.23, which is in agreement with the calculated result. The calculations reveal that the primary reason for the variation of γ is the different trends in the spin and orbital magnetic moments of the neighboring Co atoms of Ir, especially the linear increase of the latter. An investigation into the electronic structure indicates that the increase in these orbital magnetic moments is due to the appearance of 3d unoccupied minority states moving towards the Fermi level, which is induced by the local lattice distortion centered at Ir. Our findings provide the important γ data for the applications of CoIr soft magnetic films in high-frequency electromagnetic and spintronic devices, and will provide guidance in the understanding of the dynamic magnetic properties in disordered binary magnetic alloys.