Surface Roughness Effects on Magnetization Reversal of Magnetic Ring Elements
The effect of surface roughness on magnetoresistance of permalloy ring structure is investigated. Microstructured permalloy rings with surface roughness varying from 4.2 to 21 nm were fabricated using electron beam lithography and a chemical etching process. It is found experimentally that the first and second nucleation fields decrease obviously with the surface roughness increasing, and the field range for the flux-closure state is not associated with surface roughness. The results indicate that surface roughness in permalloy ring structure is an important factor that influences the magnetic behaviors of the ring. This result can provide important information for future designs of ring-shaped magnetic devices.
A permalloy zigzag structure based magnetic bio-sensor
A magnetic fluid consisting of Fe3O4 magnetic nanoparticles is embedded inside cells by intracellular uptake. A micro-fabricated magnetic zigzag-shaped surface structure is studied for use as a biosensor. We have developed a MOKE magnetometer based methodology to measure the different hysteresis loop signals between cells with and without being placed on zigzag sensors. Adding the magnetic cells on the structure decreases the coercivity from the magneto-optical Kerr effect (MOKE) signal of zigzag magnetic thin films because of the magnetic properties of superparamagnetic nanoparticles. The magnetoresistance measurement observed is that the switching fields of the zigzag structure with magnetic cells are significantly increased compared to the case without cells in the hard axis of the external field applied.
Structure and Magnetic Properties of Etched NiFeCo Films
The effect of chemical etching on the surface relief of NiFe and NiFeCo films and their magnetic parameters is studied. Electron micrograph analysis shows that during the etching inhomogeneities in the film thickness appear with a period of about 1000 A and an amplitude of the thickness fluctuations of about 100 A. This process goes along with the increase of the angular amplitude of the magnetization ripple and coercivity and is well described by Hoffmann's theory. The coercive force component stipulated by pinning of the domain walls on localized defects does not change significantly during the etching. 
 
 
 
Der Einflus des chemischen Atzvorgangs auf das Oberflachenrelief und die magnetischen Parameter von NiFe- und NiFeCo-Schichten wird untersucht. Elektronenmikroskopische Untersuchungen zeigten, das beim Atzen Schichtdickeninhomogenitaten mit einer Periode von ca. 1000 a und Dickenanderungen von etwa 100 A entstehen. Dieser Vorgang ist begleitet von einem Anwachsen der Ripple-Winkelamplitude und der Koerzitivitat. Er last sich mit der Hoffmannschen Theorie gut beschreiben. Die durch das Haften der Befeichsgrenzen an ortsfesten Fehlstellen bedingte Koerzitivkraftkomponente zeigt wahrend des Atzens keine merkliche Veranderung.