Physical Review B
The impact of antisite disorder x on the intrinsic Gilbert damping alpha(0) in well-ordered L1(0) FePt films is investigated by time-resolved magneto-optical Kerr effect. The variation of x mainly affects the electron scattering rate 1/tau(e), while other leading parameters remain unchanged. The experimentally observed linear dependence of alpha(0) on 1/tau(e) indicates that spin relaxation is through electron interband transitions, as predicted by the spin-orbit coupling torque correlation model. Measurements at low temperature show that alpha(0) remains unchanged with temperature even for FePt with very high chemical order, indicating that electron-phonon scattering is negligible. Moreover, as x decreases, the perpendicular magnetic anisotropy increases, and the Landau g factor exhibits a negative shift due to an increase in orbital momentum anisotropy. Our results will facilitate the design and exploration of magnetic alloys with large magnetic anisotropy and desirable damping properties.
Ma, X., Ma, L., He, P., Zhao, H. B., Zhou, S. M., & Lüpke, G. (2015). Role of antisite disorder on intrinsic Gilbert damping in L 1 0 FePt films. Physical Review B, 91(1), 014438.