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We have attached single ferromagnetic particles of 8 μm diameter to the tips of microfabricated atomic force microscope cantilevers. These cantilevers were magnetized to fix the magnetization direction of the ferromagnetic particles and scanned in a controlled manner over a spin valve structure of dimension 12×8 μm2. Two dimensional image scans representing the change in resistance of the spin valve due to a scanning bead were obtained. The results are explained using a simple model where the scanning bead is treated as a pure dipole. [ABSTRACT FROM AUTHOR]

Iron containing diamond-like amorphous carbon (a-C:Fe) films were deposited by filtered cathodic vacuum arc technique. The influences of Fe content and substrate bias on the surface energy of the films were investigated. The surface energy of a-C:Fe films was determined by the contact angle measurement. Atomic force microscopy, Raman spectroscopy, and x-ray induced photoelectron spectroscopy were employed to analyze the origin of the variation of surface energy with various Fe content and substrate bias. It is found that the contact angle for water increases significantly after incorporating Fe into the films and the films become hydrophobic. The roughness of these films has no effect on the contact angle. The surface energy is reduced from 42.8 to 25 dyne/cm after incorporating Fe into the a-C film (10% Fe in the target), which is due to the reduction of both dispersive and polar component. The reduction in dispersive component is ascribed to the decrease of atomic density of the a-C:Fe films due to the increase in sp[sup 2] bonded carbon. When sp[sup 2] content increases to some extent, the atomic density remains constant and hence dispersive component does not change. The absorption of oxygen on the surface plays an important role in the reduction of the polar component for the a-C:Fe films. It is proposed that such network as (C[sub n]-O-Fe)-O-(Fe-O-C[sub n]) may be formed and responsible for the reduction of polar component. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]