Abstract
A process for reversing the magnetization of a magnetic wire with a square pad was observed by magnetic force microscopy (MFM) under an external magnetic field. A wire consisting of Ta (1.5 nm)/NiFe (20 nm) was fabricated on a thermally oxidized Si substrate by means of e-beam lithography and lift-off technique. The width and length of the wire were 150 nm and 50 μm, respectively, and the size of the connecting square pad was 0.5×0.5 μm2. The direction of the external magnetic field was set parallel to the wire axis or 30 degrees from the wire axis in the substrate plane. The MFM observation was conducted under magnetic fields ranging from -400 Oe to 400 Oe at intervals of about 50 Oe. As the field increased, the domain structure in the pad changed into a closure, and one of the domain walls was pinned at the region between the wire and the pad. The pinned domain wall disappeared when the magnetic field was increased, indicating that the magnetization reversal takes place as a result of the injection of the domain wall into the wire.
