Flexible Manipulation of Operating Range in Giant Magnetoresistance Unipolar Switch Based on Double-Pinned Spin Valve

Abstract

Giant magnetoresistance (GMR) magnetic switches have been widely investigated due to their attractive advantages such as good stability, small size, large saturation field, and high integration. However, in currently available commercial GMR unipolar switches, the operation and release points are limited to a narrow range. In this work, a modified double pinned spin valve (SV) structure is proposed to achieve a wide operating range and easy modulation of magnetic unipolar switches. In particular, a modified SV structure of Ta/NiFe/IrMn/CoFe/Ru/CoFe/Cu/CoFe/IrMn/Ta was chosen, where the large and small exchange bias fields were obtained from the bottom synthetic antiferromagnetic (SAF) structure and the top CoFe/IrMn layers, respectively. Accordingly, the operating range can be easily modulated by adjusting the thickness of top pinned CoFe layer. It is worthwhile to note that the controllable range exceeds 100Oe, which is much larger than that exhibited by current commercialized SV structure. Furthermore, in the patterned sample having the modified double pinned SV, the operation and release points are independent of length and width. The reason is attributed to the exchange bias field, which weakens the impact of shape anisotropy. In addition, this result also facilitates the simplification of the design process. That is to say, the proposed modified double pinned SV offers a broad application region for GMR magnetic unipolar switches and reveals a new paradigm for the development of next-generation magnetic sensors.