Flux-enhanced giant magnetoresistive head design and simulation

The possibility of introducing a back flux-guide to increase the efficiency of a shielded giant magnetoresistive (GMR) head was studied. The flux-guide instead of the air effectively increases flux at the top of the GMR element, which leads to an increase of GMR head's sensitivity. The flux distribution was calculated by a two-dimensional (2-D) finite element method. In the simulation, the shield to shield spacing, free layer thickness, and GMR element height are assumed to be 90 nm, 4 nm, and 100 nm, respectively. Parameters such as permeability, thickness and height of flux-guides and spacing between the GMR element and flux-guides have been taken into account. The detailed magnetization distribution is simulated using a three-dimensional (3-D) micromagnetic modeling. A back flux-guide with permeability of more than 100, thickness of more than 10 nm, as well as short spacing between the element and flux-guide enhances the sensor's sensitivity. After optimization, the sensitivity of flux-enhanced magnetic tunnel junctions (MTJ) GMR head can be 40% higher than that of the conventional MTJ GMR head.