Magnetization damping in epitaxial CrO$_{2}$ (110)

Epitaxial CrO$_{2}$ thin films were grown on TiO$_{2}$ (110) substrates using chemical vapor deposition (CVD) using a CrO$_{3}$ precursor as described elsewhere [1]. In-plane angular dependent ferromagnetic resonance (FMR) measurements confirm a uniaxial in-plane anisotropy with the easy axis along the c-axis. Frequency dependent FMR measurements were carried out over a frequency range from 7-60 GHz along the easy axis of the film. The resonance field dependence on the microwave frequency is well described by the Kittel formula, enabling the determination of M$_{eff}$ and $\gamma $ of the films. The ferromagnetic resonance linewidth depends only weekly on the microwave frequency: the linewidth has a minimum around 20 GHz and increasing linearly for larger frequencies with a very small slope. Based on this we estimate the Gilbert damping constant (intrinsic) to be of the order 10$^{-4}$, i.e. very small. The main contribution to the magnetization relaxation is extrinsic in nature and can therefore be further optimized. References: [1]: X. W. Li, A. Gupta, and G. Xiao, Appl. Phys. Lett. \textbf{75}, 713 (1999).