The influence of shape and structure on the Curie temperature of Fe and Co nanoparticles

Evans, R, Nowak, U, Dorfbauer, F, Schrefl, T, Mryasov, O, Chantrell, R and Grochola, G 2006, 'The influence of shape and structure on the Curie temperature of Fe and Co nanoparticles', Journal of Applied Physics, vol. 99, pp. 08G703-1-08G703-3.


Document type: Journal Article
Collection: Journal Articles

Title The influence of shape and structure on the Curie temperature of Fe and Co nanoparticles
Author(s) Evans, R
Nowak, U
Dorfbauer, F
Schrefl, T
Mryasov, O
Chantrell, R
Grochola, G
Year 2006
Journal name Journal of Applied Physics
Volume number 99
Start page 08G703-1
End page 08G703-3
Total pages 3
Publisher American Institute of Physics
Abstract We have investigated the effect of lattice fluctuations on the magnetic properties of nanoparticles of Fe and Co. Atomic structures were simulated using a molecular-dynamic approach, with the system slowly cooled into the ordered phase. The magnetic properties were then simulated using an atomistic approach using a classical spin Hamiltonian taking into account the long-range nature and atomic separation dependence of the exchange. The magnetic properties are found to be affected by both the particle shape and the lattice fluctuations. For a perfectly ordered lattice we find that a spherical particle has a larger magnetization for a given temperature than a cube containing the same number of atoms. We have also studied the effect of lattice fluctuations. This involves a comparison of M (T) for two cases, firstly, a nanoparticle with a fixed lattice corresponding to the low-temperature annealed state (T=20 K), and secondly a nanoparticle with a lattice structure equilibrated at the temperature T, the latter case being subject to fluctuations in the lattice spacing, and the nanoparticle shape. The dynamic structure gives rise to a reduction in the magnetization and Tc, which is a finite size effect to be considered beyond others such as the reduction in coordination at the nanoparticle surface.
Subject Surfaces and Structural Properties of Condensed Matter
Keyword(s) Curie temperature
Fe and Co nanoparticles
applied physics
DOI - identifier 10.1063/1.2167636
Copyright notice © 2006 American Institute of Physics.
ISSN 0021-8979
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