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Effects of interactions on the relaxation processes in magnetic nanostructures

Effects of interactions on the relaxation processes in magnetic nanostructures
Effects of interactions on the relaxation processes in magnetic nanostructures
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.
1550-235X
1-8
Atkinson, Lewis J.
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Ostler, Thomas A.
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Hovorka, O.
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Wang, K.K.
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Lu, B.
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Ju, G.P.
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Hohlfeld, J.
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Bergman, B.
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Koopmans, B.
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Chantrell, Roy W.
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Atkinson, Lewis J.
d71238fe-a060-47a1-9455-d9d388e6acdb
Ostler, Thomas A.
d2ff1f05-1e38-4470-b6cc-70c40fc0b896
Hovorka, O.
a12bd550-ad45-4963-aa26-dd81dd1609ee
Wang, K.K.
08b63fab-f7d5-4989-a83b-83eca3617d46
Lu, B.
4185d9d6-ae6d-4ae2-a8e6-377cfcd4d206
Ju, G.P.
99e9320f-da43-47dd-b237-f1a814c496e4
Hohlfeld, J.
9ae196b0-c573-4f4d-9f9b-e05f6fdd642b
Bergman, B.
1536060d-9a02-4be6-a378-92409dd6a3ae
Koopmans, B.
37d09bec-d124-4bef-a6a0-71bccb4ea2dd
Chantrell, Roy W.
e302f8d2-4450-4d1e-a944-50f40e93e7db

Atkinson, Lewis J., Ostler, Thomas A., 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 (134431), 1-8. (doi:10.1103/PhysRevB.94.134431).

Record type: Article

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.

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Accepted/In Press date: 4 October 2016
e-pub ahead of print date: 28 October 2016
Published date: 28 October 2016
Organisations: Computational Engineering & Design Group

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Local EPrints ID: 403385
URI: https://eprints.soton.ac.uk/id/eprint/403385
ISSN: 1550-235X
PURE UUID: 6897bbff-b50d-4427-bf22-875b2c2fda80

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Date deposited: 30 Nov 2016 14:21
Last modified: 09 Jan 2018 17:41

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