Effect of a Cu buffer layer on the structural, chemical and magnetic properties of Co layers

•The hysteresis loop varies with Cu buffer layer thickness.•The coercivity of the Co varies with Cu buffer layer thickness.•The chemical state of Co 2p changes across the interface.

The effects of a Cu buffer layer on the Co/Cu bilayer system grown on Si(100) were examined from the magneto-optical Kerr effect and by X-ray photoelectron spectroscopy. The structural, magnetic and chemical properties of Co thin films varied with the Cu buffer layer thickness. As the Cu buffer layer thickness was varied, the coercivity of the Co/Cu bilayer increased and reached saturation with further increases in Cu buffer layer thickness. Furthermore, the structural changes of Co layer were observed. The depth-dependent chemical profile across the interfaces showed a change in the chemical state of the Co 2p core-level across the interface, which might be the physical origin of the enhanced coercivity.