Edge effect on coercive field of GMR sensors with meander line structure

Edge effect plays a major role on magnetic properties in permalloy microstructures. To perform high dynamic range, the meander line has been used in giant magnetoresistance (GMR) sensor for increasing the sensor active area. In this paper, we fabricated GMR sensors with various edge structures by using a photolithography and e-beam evaporation system. The device properties are measured by magnetoresistance (MR) system and compared with Object Oriented MicroMagnetic Framework (OOMMF) simulations. Magnetic moment and domain states were analyzed with respect to the edge shapes. The round corners reveal more the formation of magnetic vortex which means lowered magnetostatic energy in the GMR sensor. We found out that by altering the geometry of the edges on the GMR sensors, we can control the coercive field. When the edge structure is circular rather than rectangular, the coercive field is respectively found to be 37.5 Oe rather than 57.5 Oe, yielding a 15% variation rate by utilizing this edge effect.