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.
Classical model of extrinsic ferromagnetic resonance linewidth in ultrathin films
This paper describes a classical version of the two-magnon model of ferromagnetic resonance linewidth in inhomogeneous magnetic thin films. The ferromagnetic resonance line broadening due to inhomogeneity is described in terms of film properties and the statistical properties of the inhomogeneity. Analytical results for the case of ultrathin films in the limit of zero damping are compared with numerical results computed with finite damping.
Microwave Resonance and Relaxation of Manganese Iron Ferrites
Microwave resonance measurements are reported at 16.85 Gc/sec in the temperature range 1.5° to 300°K for single crystals of composition Mn x Fe3−x O4 with x = 1.318, 1.007, and 0.990. For x = 1.318, the linewidth and the g factor, if this is calculated in the usual way, both pass through maxima as a function of temperature. These effects are compared to the predictions of a slow relaxation model, and indicate a splitting of a low‐lying pair of energy levels of about 7.5 cm−1, and relaxation times across these levels of about 10−11 sec. The specimens close to manganeseferrite also show these relaxation effects but on a much reduced scale. They give splittings and relaxation times similar to those above. Sharp peaks in the linewidth as a function of orientation were found at [110] directions at 4.2°K and below, and were similarly dependent on composition. It is suggested that the slow relaxation is associated with manganese ions of some sort.