Exchange bias in Ag/FeCo/Ag core/shell/shell nanoparticles due to partial oxidation of FeCo intermediate shell

Recently we developed magnetic-plasmonic Ag/FeCo/Ag core/shell/shell nanoparticles for the purpose of biological applications. In these heterostructured nanoparticles, exchange bias is observed as a result of the formation of an interface between ferromagnetic FeCo and antiferromagnetic CoxFe1−xO due to the partial oxidation of the FeCo intermediate shell. In this study we thoroughly characterized the surface oxide layer of the FeCo shell by XPS, XRD and SQUID magnetometer.