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.
Wavy ferromagnetic device as single cell detection
We demonstrate a design of using a wavy permalloy thin film as a cell sensing device for the purpose of single magnetic cell detection. The magnetoresistance curve (MR curve) differs according to the single magnetic cell attached to the surface. By analyzing the MR curves, we can determine the sensing capability of the permalloy magnetic film device. Our results indicate that the sensitivity of the permalloy film sensing devices with wavy surface is much higher than the devices with flat surface. When a single magnetic cell is captured by the wavy surface of the permalloy film, the switching field of the film increase which is caused by the stray field of the magnetic cell. We discover that the highest sensitivity occurs when the direction of the magnetic field is along the Z-axis, and there is significant potential for the application of cell detection.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.