Controlling the relaxation of magnetization in magnetic nanostructures is key to optimizing magnetic storage device performance. This relaxation is governed by both intrinsic and extrinsic relaxation mechanisms and with the latter strongly dependent on the interactions between the nanostructures. In the present work we investigate laser induced magnetization dynamics in a broadband optical resonance type experiment revealing the role of interactions between nanostructures on the relaxation processes of granular magnetic structures. The results are corroborated by constructing a temperature dependent numerical micromagnetic model of magnetization dynamics based on the Landau-Lifshitz-Bloch equation. The model predicts a strong dependence of damping on the key material properties of coupled granular nanostructures in good agreement with the experimental data. We show that the intergranular, magnetostatic and exchange interactions provide a large extrinsic contribution to the damping. Finally we show that the mechanism can be attributed to an increase in spin-wave degeneracy with the ferromagnetic resonance mode as revealed by semianalytical spin-wave calculations.

Without any post physical or chemical patterning a Tl-base high temperature superconducting film has been observed to pattern spontaneously on SrTiO3 (100) by liquid-gas-solidification process. The film exhibits the morphology of a microelectric network in which the directions of growth of the crystal walls follow the directions of the SrTiO3 (100) substrate. The crystal walls consisting of Tl-1223 and Tl-1212 phases are 0.25–1 μm wide, 2 μm high, and a few millimeters long. These walls are proposed to grow from independent nucleation sites and coalescence to form semiconductive junctions. The network exhibits a superconducting transition onset at 113 K and approaches zero resistance at 95 K. Below 95 K, the resistance increases exponentially with decreasing temperature. This strongly suggests that the films form a natural superconductor/semiconductor/superconductor junction array.