Spin Disorder and Magnetic Anisotropy in Fe3O4 Nanoparticles

Abstract

We have studied the magnetic behavior of dextran-coated magnetite (Fe${}_3$O${}_4$) nanoparticles with median particle size $⟨d⟩=8$ $nm$. Magnetization curves and in-field Mössbauer spectroscopy measurements showed that the magnetic moment $M_S$ of the particles was much smaller than the bulk material. However, we found no evidence of magnetic irreversibility or non-saturating behavior at high fields, usually associated to spin canting. The values of magnetic anisotropy $K_{eff}$ from different techniques indicate that surface or shape contributions are negligible. It is proposed that these particles have bulk-like ferrimagnetic structure with ordered A and B sublattices, but nearly compensated magnetic moments. The dependence of the blocking temperature with frequency and applied fields, $T_B(H,\omega )$, suggests that the observed non-monotonic behavior is governed by the strength of interparticle interactions.

11 pages, 7 figures, 3 Tables

References in corpus (2)

• Role of surface disorder on the magnetic properties and hysteresis of nanoparticles
• Ferrimagnetism and spin canting of ZnFe2O4 nanoparticles embedded in ZnO matrix

Cited by in corpus (7)

• Magnetic irreversibility and Verwey transition in nano-crystalline bacterial magnetite
• Magnetic hydrogels derived from polysaccharides with improved specific power absorption: potential devices for remotely triggered drug delivery
• The effect of the magnetically dead layer on the magnetization and the magnetic anisotropy of the dextran coated magnetite nanoparticles
• Superparamagnetic dynamics and blocking transition in Fe${}_3$O${}_4$ nanoparticles probed by vibrating sample magnetometry and muon spin relaxation
• Unraveling nanoscale magnetic ordering in Fe3O4 nanoparticle assemblies via x-rays
• Response of the Verwey transition in magnetite to a controlled point-like disorder induced by 2.5 MeV electron irradiation
• Magnetization Reversal Across Multiple Serial Barriers in a Single Fe${}_3$O${}_4$ Nanoparticle