Development of Ultimate Low-Noise Magnetic Field Sensors Using Novel Sensing Layer in Magnetic Tunnel Junctions for Sensing-Driven Society

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K15429
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: Tohoku University
• Principal Investigator: Al-Mahdawi Muftah 東北大学, 先端スピントロニクス研究開発センター, 助教 (90729576)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: spintronics / sensors / YIG / PtMn / Vortex

Outline of Final Research Achievements

The spintronic sensors based on magnetic tunnel junctions (MTJs) are promising in the domains of Internet-of-Things (IoT), automotive, biomedical, etc. A main obstacle is the intrinsic magnetic noise processes. In this research, we investigated the origin of noise in MTJ sensors, and we designed new thin-film sensing layers. First, we clarified the microscopic origins of magnetic noise using magnetic domain imaging. We found that the magnetic domain wall fluctuations are a major contribution to low-frequency noise. Secondly, we investigated new sensing layers of: (a) permalloy/platinum manganese exchange-coupled layers, (b) vortex formation in circular sensing devices, and the control of sensitivity in the vortex-type MTJs, and (c) yttrium iron garnet thin films.

Free Research Field

Spintronics

Academic Significance and Societal Importance of the Research Achievements

We clarified an origin of magnetic noise in magnetic tunnel junction sensors, and developed new sensing devices and materials. This advances understanding of magnetic fluctuations in micro-sized sensors, and adds to applications in cheap low-power sensors, such as IoT and biomedical fields.