Magnetic and magneto-optical properties of Fe3O4 nanoparticles modified with Ag.

• Fe 3 O 4 nanoparticles modified with Ag were synthesized with thermal decomposition method. • Nanoparticles morphology and size do not depend on Ag concentration. • The Ag effect on nanoparticles magnetic properties was studied. • Strong influence of Ag on visible magnetic circular dichroism was revealed and discussed. Effect of Ag inclusions on magnetic properties and magnetic circular dichroism (MCD) of Fe 3 O 4 nanoparticles (NPs) in the mixed system of Fe 3 O 4 and Ag NPs in dependence on the relative concentration of the components is presented. The samples were synthesized by the thermal decomposition of the mixture of constant concentration of Fe(NO 3) 3 ·9H 2 O and varied concentration of AgNO 3. The synthesized powdered samples consisted of Fe 3 O 4 and Ag NPs located very close with each other, and in the most cases the Fe 3 O 4 NPs were bordered with the Ag nanocrystals. The Ag introducing in the samples does not effect, practically, in the Fe 3 O 4 NPs morphology and size distribution. At the same time, Ag NPs in the powdered samples cause a decrease in the Fe 3 O 4 NPs magnetization and shift of the blocking temperature to lower temperatures, both approximately proportional to the Ag concentration. Most significant changes are revealed in the MCD spectra in the energy region of 1.2–2.2 eV. We have discussed the influence of the Ag NPs on the MCD spectra features in terms of the charge-transfer electron transitions. [ABSTRACT FROM AUTHOR]