單分子層官能基對鐵磁性薄膜磁性質改變之研究

Abstract

We demonstrate the tuning of magnetic properties of ferromagnetic (FM) thin films by reversing the functional groups of a molecular mono-underlayer. We construct a bilayer thin film system which consists of a FM material and an organic mono-layer by applying organic molecules to form a molecular mono-layer on the glass substrate, then depositing the FM thin film onto the organic molecules by sputtering. We design the experiment to use only one kind of molecule to create two different kinds of surfaces by reversing the functional groups of the molecular mono-layer. By simply reversing the functional groups of the mono-layer in direct contact with the FM thin films, two kinds of surfaces have been designed to be hydrophilic or hydrophobic. Two FM materials are studied. One is CoFe, and the other is permalloy (Py). In the system of CoFe thin films we found the coercivity of hydrophobic molecular mono-layer covered with CoFe films is enhanced. On the other hand, in the system of Py thin films we found the FM behavior disappears at room temperature when the hydrophobic molecular mono-layer is covered with Py films, and this phenomenon is correlated to the surface morphology. The study in this thesis is helpful to organic spintronics and could be used to fabricate organic spintronics, which is a frontier of spintronics.