Exchange bias effect in Au-Fe₃O₄nanocomposites

Abstract

We report exchange bias (EB) effect in the Au-Fe3O4 composite nanoparticle system, where one or more Fe3O4 nanoparticles are attached to an Au seed particle forming ‘dimer’ and ‘cluster’ morphologies, with the clusters showing much stronger EB in comparison with the dimers. The EB effect develops due to the presence of stress at the Au-Fe3O4 interface which leads to the generation of highly disordered, anisotropic surface spins in the Fe3O4 particle. The EB effect is lost with the removal of the interfacial stress. Our atomistic Monte Carlo studies are in excellent agreement with the experimental results. These results show a new path towards tuning EB in nanostructures, namely controllably creating interfacial stress, and opens up the possibility of tuning the anisotropic properties of biocompatible nanoparticles via a controllable exchange coupling mechanism.

Probing core and shell contributions to exchange bias inCo/Co3O4nanoparticles of controlled size

“…These observations are in agreement with what has been found also at the interface of Au-Fe 3 O 4 composites [48,49], Co/Co 3 O 4 nanooctahedra [25], and Fe oxidized cubic NP [50], suggesting that lattice mismatch correlates with changes in magnetic anisotropy. There is also evidence that lattice strain induced by acoustic waves applied to some magnetic structures [51,52] can influence the value of the anisotropy constant and its easy axis.…”

Simultaneous enhancements of polarization and magnetization in epitaxialPb(Zr0.52Ti0.48)O3/Mukherjee1, Hordagoda2, Lampen3 et al. 2015Phys. Rev. B29390View full textAdd to dashboardCite

“…A χ T (H) curve for a conventional ferromagnetic material in which H (where is H is perpendicular to the easy-axis) is swept from positive to negative saturation shows singularities at the anisotropy fields (H = ± H k ) and the switching field (H = H s ) [43]. We note that in practice the switching peak or anisotropy peaks may be absent from the χ T profile, depending on the magnetic nature of the sample [37,[44][45][46][47] …”

Plasmonic nanodevice with magnetic funcionalities: fabrication and characterization

“…The first one consists in hybrid structures where both the plasmonic and ferromagnetic elements are nanometric. In the last years, the recent advances in colloidal chemistry allowed to develop complex nanoparticles with ferromagnetic and plasmonic elements with different architectures as dimers [24], flowers [25] or core-shell structures [26][27][28] that exhibit ferromagnetic properties and surface plasmon resonances. Patterning of multilayers to form nanometric elements has been also studied, mainly in order to tune the SPR [29][30][31].…”