A Three-Dimensional Magnetic Flux Guide for Magnetic Tunnel Junction Sensors

• Published in: IEEE transactions on magnetics Vol. 58; no. 5; pp. 1 - 5
• Main Authors: Li, Peisen, Pan, Long, Hu, Yueguo, Che, Yulu, Hu, Jiafei, Pan, Mengchun, Du, Qingfa, Yu, Yang, Sun, Kun, Zhang, Xinmiao
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplification; Decoupling method; Magnetic field measurement; Magnetic fields; Magnetic films; Magnetic flux; Magnetic flux guides (MFG); Magnetic sensors; Magnetic structure; Magnetic tunneling; Magnetism; Miniaturization; Numerical models; numerical studies; Orthogonality; Sensors; Three axis; three-dimensional; Tunnel junctions
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2022.3154539

Three-axis magnetic sensors, sensing the three components of a magnetic field, have important applications in many fields. However, the three-axis magnetic sensors assembled with three uniaxial sensors oriented in orthogonal directions (<inline-formula> <tex-math notation="LaTeX">x </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">y </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">z </tex-math></inline-formula> vectors) are facing many problems. In this article, the design concept of a new three-dimensional (3-D) magnetic flux guide (MFG) was proposed. The 3-D MFG converts the component of the magnetic field perpendicular to the sensor film plane (<inline-formula> <tex-math notation="LaTeX">z </tex-math></inline-formula>-direction) into that of the field in the sensor film plane ( xy plane ) through the "<inline-formula> <tex-math notation="LaTeX">\bot </tex-math></inline-formula>"-like magnetic structure, and then converts all the xy plane components into that in the same direction via a special magnetic film with 45° gap. As a result, the three components of magnetic field are converted into the same direction to be measured. Meanwhile, the decoupling method of three-component magnetic field was extracted from outputs of the four xy plane magnetic field measuring (MFM) units. Moreover, a numerical model was established to analyze amplification factors of three-component magnetic field and optimize the dimension parameters. The simulation results show that the proposed 3-D MFG can enhance the magnetic field with an amplification factor of about 67 times for the <inline-formula> <tex-math notation="LaTeX">z </tex-math></inline-formula>-direction component and about 51 times for the xy plane component. Thus, the 3-D MFG has large magnetic field magnification factors in all three directions, and can be realized by the integrated preparation method, which has the advantages of low non-orthogonality and miniaturization.