Structural determination and magnetic properties for Co–rubrene composite films on Si(1 0 0)

Abstract

Because of the potential uses toward low-cost and flexible-substrate-based electronics, semiconducting organic materials have attracted much attention. In this contribution, structures and magnetic properties of Co–rubrene composite films on Si(100) have been studied by employing atomic force microscopy (AFM) and magneto-optic Kerr effect techniques. For composite films prepared by co-depositions of Co and rubrene on Si(100), the surface is smooth while a layered distribution of Co atoms is detected. For thick composite films, surfactant effects of rubrene molecules cause smooth surfaces and reduced interaction at the film/Si interface. For thin composite films, the formation of separated Co clusters in the films results in a larger coercive force due to the imperfection introduced by rough interface to impede the magnetization reversal. By increasing the rubrene concentration, more Co/rubrene interfaces are introduced in the composite films and the more rubrene served as a surfactant enhances the quality of the films. These information are valuable for future applications combining organic semiconductor and spintronics.