Laser-induced magnetization dynamics of lanthanide-doped permalloy thin films

We investigate the effect of Ho, Dy, Tb, and Gd impurities on the femtosecond laser-induced magnetization dynamics of thin Permalloy films using the time-resolved magneto-optical Kerr effect. Varying the amount of Ho, Dy, Tb content from 0% to 8%, we observe a gradual change of the characteristic de...

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Bibliographic Details
Published in:Physical review letters 2009-03, Vol.102 (11), p.117201-117201, Article 117201
Main Authors: Radu, I, Woltersdorf, G, Kiessling, M, Melnikov, A, Bovensiepen, U, Thiele, J-U, Back, C H
Format: Article
Language:English
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Summary:We investigate the effect of Ho, Dy, Tb, and Gd impurities on the femtosecond laser-induced magnetization dynamics of thin Permalloy films using the time-resolved magneto-optical Kerr effect. Varying the amount of Ho, Dy, Tb content from 0% to 8%, we observe a gradual change of the characteristic demagnetization time constant from approximately 60 to approximately 150 fs. In contrast, Gd concentrations up to 15% do not influence the time scale of the initial photoinduced magnetization loss. We propose a demagnetization mechanism that relies on strong magnetic inertia of the rare-earth dopant which stabilizes the ferrimagnetic ordering and thereby delays the demagnetization.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.102.117201