Ferromagnetic resonance and magnetic damping in C-doped Mn5Ge3

International audience2 X-band ferromagnetic resonance (FMR) was used to investigate static and dynamic magnetic properties of Mn5Ge3 and Carbon-doped Mn5Ge3 (C0.1 and C0.2) thin films grown on Ge(111). The temperature dependence of magnetic anisotropy shows an increased perpendicular magneto-crystalline contribution at low temperature with an in-plane easy axis due to the large shape contribution. We find that our samples show as small as 40Oe FMR linewidth (corresponding Gilbert damping α=0.005), for the out-of-plane direction, certifying of their very good structural quality. The perpendicular linewidth shows a minimum around 200K for all samples, which seems not correlated to the C-doping. The magnetic relaxation parameters have been determined and indicate as main extrinsic contribution the two-magnon scattering. A transition from six-fold to twofold plus fourth-fold in-plane anisotropy is observed in the FMR linewidth of Mn5Ge3C0.2 around 200K