Enhanced smoothness and magnetic properties for Co-rubrene composite films
Yong-Jhih Hou1, Cheng-Hsun-Tony Chang1, Yen-Wei Jhou1, Jyh-Shen Tsay1*
1Department of Physics, National Taiwan Normal University, Taipei, Taiwan
* presenting author:蔡志申, email:jstsay@phy.ntnu.edu.tw
Because of the potential uses of organic semiconducting materials toward low-cost- and flexible-substrate-based electronics, semiconducting organic materials have attracted much attention. Rubrene (5,6,11,12-tetraphenylnaphthacene) is the organic semiconductor with the highest carrier mobility while cobalt is widely used in magnetic recording media. In this contribution, structures and magnetic properties of Co-rubrene composite films on Si(100) have been studied by employing atomic force microscopy and magneto-optic Kerr effect techniques. For thick composite films prepared by co-depositions of Co and rubrene on Si(100), 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, the more rubrene served as a surfactant enhances the quality of the films. For composite films with a larger rubrene fraction, lower Kerr intensities are detected because more Co/rebrene interfaces are introduced in the films. These results provide valuable information for future applications in organic semiconductor and spintronics.

Keywords: rubrene , cobalt, magneto-optic Kerr effect, atomic force microscopy