Spin-glass like behaviour in strongly interacting nanocrystalline Ni embedded in SiO2

Abstract

Ni nanoparticles embedded in the SiO2 host are prepared by sol–gel route. Studies on X-ray diffraction and transmission electron microscopy confirm chemically single phase, good crystallinity and formation of nearly spherical nanoparticles with average size of 18nm. Temperature dependence of zero field cooled (ZFC) magnetization shows a broad maximum around 230K (Tmax), below which memory effect is observed in the field cooled (FC) and zero field cooled (ZFC) modes. A strong frequency dependence of ac susceptibility is observed around Tmax and the shift of peak position with frequency satisfies the dynamical scaling law with parameters close to that observed for atomic spin-glasses. At low temperature signature of spin-glass (SG) like behaviour is confirmed from the observed memory effect in the ZFC and isothermal remanent magnetization studies. The SG like behaviour is also apparent from the analysis of the relaxation mechanism.