Effects of interactions on the relaxation processes in magnetic nanostructures

Atkinson, Lewis J.; Ostler, Thomas A.; Hovorka, O.; Wang, K. K.; Lu, B.; Ju, G. P.; Hohlfeld, J.; Bergman, B.; Koopmans, B.; Chantrell, Roy W.

Abstract

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.

Citation

Atkinson, L. J., Ostler, T. A., Hovorka, O., Wang, K. K., Lu, B., Ju, G. P., …Chantrell, R. W. (2016). Effects of interactions on the relaxation processes in magnetic nanostructures. Physical Review B, 94(13), Article 134431. https://doi.org/10.1103/PhysRevB.94.134431

• Journal Article Type: Article
• Acceptance Date: Aug 10, 2016
• Online Publication Date: Oct 28, 2016
• Publication Date: Oct 1, 2016
• Deposit Date: Jun 15, 2022
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 94
• Issue: 13
• Article Number: 134431
• DOI: https://doi.org/10.1103/PhysRevB.94.134431
• Public URL: https://hull-repository.worktribe.com/output/4014677