title: Modeling the Brownian relaxation of nanoparticle ferrofluids: comparison with experiment.
abstract: OBJECTIVE
  The authors investigate the ability of current models for magnetic nanoparticles immersed in dilute ferrofluids and external sinusoidal magnetic fields to explain recent experiments in which the relaxation effects are dominated by viscous damping.
  
  
  METHODS
  The Fokker-Planck (FP) equation appropriate for the nanoparticle magnetic moment distribution corresponding to the underlying stochastic Langevin model is numerically studied and solutions compared to experimental results. The FP equation is solved using an expansion in Legendre polynomials. The polydisperse properties of the ferrofluids are incorporated into the analysis.
  
  
  RESULTS
  By using a FP approach that includes polydispersion, the authors obtain good agreement with recent experimental results using ferrofluids containing nanoparticles with average hydrodynamic diameters in the 40-120 nm range.
  
  
  CONCLUSIONS
  For nanoparticles used in recent magnetic spectroscopy experiments, the FP approach can be used to accurately model experimental data in the situation where Brownian relaxation effects are dominant and the ferrofluids are dilute.
authors: Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA. Michael.Martens@case.edu
authors: Michael A
authors: MA
authors: Martens
authors: Robert J
authors: RJ
authors: Deissler
authors: Yong
authors: Y
authors: Wu
authors: Lisa
authors: L
authors: Bauer
authors: Zhen
authors: Z
authors: Yao
authors: Robert
authors: R
authors: Brown
authors: Mark
authors: M
authors: Griswold
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D060526:Magnetic Fields; D060328:Magnetic Phenomena; D008962:Models, Theoretical; D009038:Motion; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D014867:Water / Q000737:chemistry
chemical_list: D005290:Ferric Compounds; D014867:Water; C000499:ferric oxide; D005990:Glycerol
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