Correlation between Gilbert damping and electric resistivity in Fe₉₄Co₆/GaAs single crystal thin films: A role of electron scattering

Relation between Gilbert damping and scattering of conduction electrons in 3 d transition metals is investigated. Fe₉₄Co₆ thin films were epitaxially deposited on GaAs(001) by rf magnetron sputtering. Some films were annealed in situ, and compared with the as-deposited films. The electric resistivity was smaller in the annealed films both at room and low temperatures, indicating that the scattering rate of conduction electrons was reduced by annealing. Gilbert damping was evaluated from the peak width of ferromagnetic resonance spectra. We have found that at room temperature the damping is smaller in the annealed sample (with smaller scattering rate), while at low temperature the damping is enhanced when the scattering rate is decreased. The opposite dependencies of Gilbert damping on the electron scattering rate at low and room temperatures agree with the theoretical studies based on the linear response. (paper)