Spin-orbit-coupling effects on g-value and damping factor of the ferromagnetic resonance in Co and Fe films

The spectroscopic splitting factor g and the Gilbert damping constant G are magnetic parameters accessible to ferromagnetic resonance (FMR) measurements, which apart from the magneto-crystalline anisotropy energy can provide information on the spin-orbit coupling in magnetically ordered material. Whereas the effect of spin-orbit coupling has been thoroughly investigated and is well understood in insulating transition metal compounds, in 3d-metallic magnetic compounds the microscopic mechanism still needs further clarification. Particularly in thin films and multilayers interface effects and interaction between layers can modify both spin and orbital moments leading to changes of the g-value and the Gilbert damping constant. Experimental results are presented from frequency dependent FMR measurements on Co epitaxial films grown on Cr(001) and on films of the alloy Co1-xFex (100) deposited on MgO(001), and from recent studies on Fe(100) films grown on InAs(001). The experimental data yield clear evidence of the importance of surfaces or interfaces of the films on the magnitude of orbital and spin moment.