Charge transfer, electronic transport and magnetic properties of Cu[formula omitted]Ni[formula omitted]/reduced graphene oxide nanocomposites

Abstract

Nanocomposites of magnetic nanoparticles and graphene based C structures that have finite band gap are promising materials for spintronic applications. Tuning the electronic transport and magnetic properties of such nanocomposites by the nanoparticle magnetism is desirable, and studying the underlying mechanism is intriguing. In the present work, we study the electronic transport and magnetic properties of nanocomposites of reduced graphene oxide and an alloy system Cu1−xNix (0≤x≤1) that undergoes a composition induced paramagnetic to ferromagnetic phase transition at x=xc=0.44. The nanocomposites are prepared using a combination of modified Hummer’s and reflux methods. Imaging, diffraction and spectroscopy results ascertain desired crystallinity and phase formation. Raman spectra indicate a charge transfer from the RGO sheets to the nanocomposites. Density functional theory computations confirm the occurrence of charge transfer. Electrical resistivities of the nanocomposites are found to follow thermally activated band conduction mechanism, akin to disordered semiconductors. The x-variation of activation energy is explicable in terms of the nanocomposite magnetization, which diverges at xc. Thus, the magnetism of the nanoparticles is shown to tune the electronic transport and magnetic properties of the nanocomposites via charge transfer.