Digital magnetoresistance characteristics of NiFeCo/Cu/Co spin-valve trilayers

Digital magnetoresistance (MR) properties of the sheet and patterned NiFeCo/Cu/Co spin-valve trilayer films were characterized. As reported in our previous publication, NiFeCo/Cu/Co films showed strong in-plane uniaxial magnetic anisotropy on a special template, 4°tilt-cut Si(111) wafer with a 50 Å of Cu underlayer, without any externally applied magnetic field during the deposition. In order to demonstrate the industrial applicability of NiFeCo/Cu/Co films on the specific templates for digital MR devices, dynamic and static MR measurements were performed along the easy axis of the films. For dynamic MR measurement, NiFeCo/Cu/Co films were optimized with respect to Cu spacer thickness and patterned into a stripe of high aspect ratio of 1: 200 (height: width) where the easy aids of the film was aligned along the height direction. After patterning, uniaxial magnetic anisotropy was maintained, and MR properties showed no appreciable degradation. Therefore, it was believed that the special template is effective for the uniaxial magnetic anisotropy of NiFeCo/Cu/Co films and useful in the industrial applications. MR properties of sheet and patterned trilayer films suggest that these NiFeCo/Cu/Co spin valves on the specific templates are good candidates for digital MR devices such as magnetoresistive random access memory (MRAM)