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Multiscale modeling of magnetic materials: Temperature dependence of the exchange stiffness

Atxitia, U., Hinzke, D., Chubykalo-Fesenko, O., Nowak, U., Kachkachi, H., Mryasov, O.N., Evans, R.F. (orcid.org/0000-0002-2378-8203) and Chantrell, R.W. (2010) Multiscale modeling of magnetic materials: Temperature dependence of the exchange stiffness. Physical review B. 134440. -. ISSN 1550-235X

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For finite-temperature micromagnetic simulations the knowledge of the temperature dependence of the exchange stiffness plays a central role. We use two approaches for the calculation of the thermodynamic exchange parameter from spin models: (i) based on the domain-wall energy and (ii) based on the spin-wave dispersion. The corresponding analytical and numerical approaches are introduced and compared. A general theory for the temperature dependence and scaling of the exchange stiffness is developed using the classical spectral density method. The low-temperature exchange stiffness A is found to scale with magnetization as m(1.66) for systems on a simple cubic lattice and as m(1.76) for an FePt Hamiltonian parametrized through ab initio calculations. The additional reduction in the scaling exponent, as compared to the mean-field theory (A similar to m(2)), comes from the nonlinear spin-wave effects.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 American Physical Society. This is an author produced version of a paper published in PHYSICAL REVIEW B. Uploaded in accordance with the publisher's self archiving policy.
Institution: The University of York
Academic Units: The University of York > Physics (York)
Depositing User: Repository Administrator York
Date Deposited: 18 Nov 2010 16:16
Last Modified: 01 May 2016 00:01
Published Version: http://dx.doi.org/10.1103/PhysRevB.82.134440
Status: Published
Refereed: Yes
Related URLs:
URI: http://eprints.whiterose.ac.uk/id/eprint/42658

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