Evidence on the presence of Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction in CoFe2O4@Au nano structure

• Co-Ferrite/Au core shell nanocomposites were prepared.
• The change of gold thickness affected the magnetization and nucleation field.
• The results showed the presence of RKKY interaction of the magnetic particles.
• An enhancement of the heating ability under oscillating magnetic field was obtained.

In this work, a straight forward method for preparing CoFe2O4/Au core shell nano composite is introduced. By this method, samples with different thickness of Au as shell were obtained. The crystal and micro structures of the prepared samples were studied using x-ray diffraction and TEM micrographs. The presence of plasmonic frequencies of gold nano particles was investigated by measuring absorbance spectra in the visible range. It was found that, the plasma frequency decreases with increasing the gold thickness. The effect of the gold thickness on the magnetization, nucleation field and magnetic loss were studied. The experimental measurements showed an oscillating behavior of the magnetic parameters with increasing gold thickness. These results could be explained in terms of the presence of Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction between the ferromagnetic components via the conduction electrons of the gold metal. The heating ability of the magnetic Co-Ferrite particles under high frequency magnetic field was enhanced by the presence of the gold as a shell.