Effects of interactions on the relaxation processes in magnetic nanostructures

ATKINSON, Lewis J., OSTLER, Thomas, HOVORKA, O., WANG, K. K., LU, B., JU, G. P., HOHLFELD, J., BERGMAN, B., KOOPMANS, B. and CHANTRELL, Roy W. (2016). Effects of interactions on the relaxation processes in magnetic nanostructures. Physical Review B, 94 (13), p. 134431.

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Official URL: http://journals.aps.org/prb/abstract/10.1103/PhysR...
Link to published version:: https://doi.org/10.1103/PhysRevB.94.134431


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.

Item Type: Article
Departments - Does NOT include content added after October 2018: Faculty of Science, Technology and Arts > Department of Engineering and Mathematics
Identification Number: https://doi.org/10.1103/PhysRevB.94.134431
Page Range: p. 134431
Depositing User: Thomas Ostler
Date Deposited: 02 Mar 2017 11:37
Last Modified: 18 Mar 2021 04:05
URI: https://shura.shu.ac.uk/id/eprint/15272

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