Tailoring Spin Relaxation in Thin Films by Tuning Extrinsic Relaxation Channels
The importance of extrinsic spin relaxation processes such as magnon-magnon scattering for the overall damping in ferromagnetic thin films has been shown for low relaxation rate systems. Due to its anisotropic behavior, it offers an opportunity for controlling and tailoring the spin relaxation. In this paper, a ferromagnetic resonance study of a system with pure Gilbert damping Fe94.5Si5.5/MgO(001) is shown. Fe3Si/MgO(001) systems with native magnon-magnon scattering are discussed. Possibilities for inducing magnon-magnon scattering by volume and surface defects in these systems are presented, offering a method for controlled tailoring of the overall damping in thin films.
Separation of the two-magnon scattering contribution to damping for the determination of the spin mixing conductance
We present angle dependent measurements of the damping properties of epitaxial Fe layers with MgO, Al and Pt capping layers. Based on the preferential distribution of lattice defects following the crystal symmetry, we make use of a model of the defect density to separate the contribution of two-magnon scattering to the damping from the isotropic contribution originating in the spin pumping effect, the viscous Gilbert damping and the magnetic proximity effect. The separation of the two-magnon contribution, which depends strongly on the defect density, allows for the measurement of a value of the effective spin mixing conductance which is closer to the value exclusively due to spin pumping. The influence of the defect density for bilayers systems due to the different capping layers and to the unavoidable spread in defect density from sample to sample is thus removed. This shows the potential of studying spin pumping phenomena in fully ordered systems in which this separation is possible, contrary to polycrystalline or amorphous metallic thin films.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.