Novel Magnetic Flux Guiding Structure of Magnetoresistive Sensor for Increased Sensitivity

A novel magnetic flux guiding structure that connects laminated micro magnetic flux concentrators (MFCs) and magnetic tunnel junctions (MTJs) for increased sensitivity in magnetoresistive sensors is studied. In this novel structure, with only deposited laminated micro MFCs, a gain of about 24 in magnetic flux density is achieved, which provides a new approach to further improving the sensitivity of magnetoresistive sensors with small footprints. Also, with external MFCs added, a very high overall gain of about 2760 is achieved, and a sensitivity as high as $4.71 \times 10$ 3%/Oe ( $4.71 \times 10$ 4%/mT) in magnetoresistive sensors at room temperature is demonstrated. Besides, the noise level is discussed. The studied structure paves the way for the development of ultrahigh-sensitivity magnetoresistive sensors at room temperature.