Effect of Buffer Layers on the Properties of NiFe/Cu/NiFe Trilayers

The properties of NiFe/Cu/NiFe trilayers with different buffer and cap layers are investigated. It is found that the properties of the NiFe/Cu/NiFe trilayers with a 50 Å NiFeCr buffer layer and a 50 Å NiFeCr cap layer exhibit a triangle transfer curve with a negligible hysteresis, showing a Giant magnetoresistance (GMR) ratio of 5.4%, and a saturation field of 272 Oe. In comparison, the trilayer deposited on a 50 Å Cu exhibits no GMR effect. It is found that the interface roughness and microstructure, especially the crystallographic quality of the films have played key roles in determining the properties of NiFe/Cu/NiFe trilayers. With NiFeCr as buffer layer, antiferromagnetic coupling can be well established in the NiFe/Cu/NiFe trilayers, leading to an excellent GMR effect. The NiFe/Cu/NiFe trilayers with a NiFeCr buffer layer also exhibit a good thermal stability, making it suitable for sensing device applications.