On the ferromagnetic Cu nanocrystals

Abstract

A room temperature ferromagnetism (RTFM) is observed in Cu nanocrystals (NCs) capped with amine ligands in contrast to the literature survey indicating presence of ferromagnetic ordering only in S-capped NCs. Cu-N bonds along with Cu-O bonds induce the changes in electron energy levels producing holes in 3d energy levels. Presence of Cu-O and Cu-N bonds is asserted by infra-redspectroscopy. The electron spin resonance measurements (ESR) indicate presence of Cu2+ions on metallic Cu nanocrystals and thus corroborate the prediction. The present studies support the conjecture that ferromagnetic ordering in metal nanocrystals is a manifestation of surface uncompensated spins. Magnetization as a function of temperature unravels the exchange mechanism.