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Magnetic Domains

Magnetic Domains. Exchange Interactions. Dipolar Interactions. Atom. Competition between exchange and dipolar interactions leads to domain formation. Magnetic Nanoparticle Arrays. Vary Size. Vary Spacing. Vary Ordering. Nanoparticle Synthesis.

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Magnetic Domains

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  1. Magnetic Domains Exchange Interactions Dipolar Interactions Atom Competition between exchange and dipolar interactions leads to domain formation

  2. Magnetic Nanoparticle Arrays Vary Size Vary Spacing Vary Ordering

  3. Nanoparticle Synthesis • Fe synthesized using air free solution chemistry methods • Thermal decomposition of Fe(CO)5 in octyl ether • Particles coated with surfactant • Washed with ethanol and dispersed in hexane D. F. Farrell, S. A. Majetich, and J. P. Wilcoxon, J. Phys. Chem.107, 11022-11030 (2003).

  4. Heterogeneously Nucleated Fe 7.0 ± 0.8 nm 9.2 ±0.7 nm Seeded with Pt (Fe:Pt ~1000:1)

  5. Homogeneously Nucleated Fe 9.1 ± 0.9 nm 11.2 ± 1.0 nm 19 nm No Pt salt, larger amount of oleic acid surfactant

  6. Electron Diffraction HeterogeneousHomogeneous Fe oxide rings dominate

  7. Blocking Temperatures Field-cooled, Zero field-cooled Magnetization 7.0 ± 0.8 nm 11.2 ± 1.0 nm 0.01vol. % H = 200 Oe Heterogeneously Nucleated Homogeneously Nucleated 2 Blocking T’s: Fe, Fe oxide

  8. Particle Concentration Found from calibrated x-ray fluorescence of solutions* Use to determine total mass of Fe ss * Dr. Jess P. Wilcoxon, Sandia National Laboratories

  9. Oxide Shell Thickness • Relate ss of particles to weighted average of ss of Fe core and Ms of oxide shell ss,partmpart = ss,coremcore + ss,shellmshell

  10. Return to Home Page

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