Finite size effects in L1{sub o}-FePt nanoparticles
- HGST, a Western Digital company, 3403 Yerba Buena Road, San Jose, California 95135 (United States)
Finite size effects on the temperature dependence of the uniaxial magnetic anisotropy, longitudinal and transverse susceptibilities and specific heat are examined for L1{sub o}-ordered FePt nanoparticles using an atomistic model based on an effective classical spin Hamiltonian. At low temperatures below criticality, we study the intrinsic uniaxial magnetic anisotropy energy (MAE) K{sub 1} and its scaling with magnetization K{sub 1}(T)∼M{sub s}(T){sup δ} and using Langevin dynamics simulations we show that the dependence of the exponent δ on the size L and aspect ratio of the grain arises from decomposition of the MAE into bulk and surface dependent terms. Monte Carlo simulations in the critical regime near the Curie temperature T{sub c}, show that the temperature variation of the specific heat and longitudinal susceptibility is given by finite size scaling relations c=L{sup α/ν}c{sup ~}(L{sup 1/ν}ϵ) and χ=L{sup γ/ν}χ{sup ~}(L{sup 1/ν}ϵ), respectively, where ϵ=(T−T{sub c})/T{sub c} is the reduced temperature, and the susceptibility scaling function χ{sup ~} can be approximated by a Lorentzian. Our estimates of the critical exponents α,γ, and ν appear to be in agreement with the universality class of the 3D Ising model.
- OSTI ID:
- 22266124
- Journal Information:
- Journal of Applied Physics, Vol. 114, Issue 23; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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