Structural and magnetic properties of Co films on highly textured and randomly oriented C-60 layers

Abstract

The structural and magnetic properties of Co/C-60/pentacene and Co/C-60 thin film structures were investigated. Atomic force microscopy and x-ray reflectivity analysis show that the presence or absence of a pentacene buffer layer leads to a highly textured or randomly oriented C-60 layer, respectively. A Co film deposited on a randomly oriented C-60 layer penetrates into the C-60 layer when it is deposited at a slow deposition rate. The Co penetration can be minimized, regardless of the Co deposition rate, by growth on a highly textured and nanostructured C-60/pentacene layer. Vibrating sample magnetometry measurements show that the saturation magnetization of Co/C-60/pentacene is significantly reduced compared to that of Co/C-60. On the other hand, the Co penetration does not seem to have an effect on the magnetic properties, suggesting that the structural properties of the Co and C-60 layer, rather than the Co penetration into the organic C-60 layer, are critical to the magnetic properties of the Co/C-60. (C) 2015 Elsevier B.V. All rights reserved.