journal article·2021-01-01Open access

Highly-sensitive magnetic sensor for detecting magnetic nanoparticles based on magnetic tunnel junctions at a low static field

Z. Jin, Thomas Myeongseok Koo, Myeong Soo Kim, M. Al-Mahdawi, M. Oogane, Y. Ando, Young Keun Kim

AIP Advances· Volume 11· Issue 1

Abstract

Magnetic sensors to detect magnetic nanoparticles (MNPs) towards biomedical applications require very high sensitivity at low magnetic fields. Here we report a magnetic sensor consisting of a magnetic tunnel junction (MTJ) with a synthetic antiferromagnetic free layer. This sensor exhibits a low magnetic anisotropy and sensitivities of over 18%/Oe at low fields in the range of 0 to 3 Oe. We employ superparamagnetic MNPs with a large diameter of 200 nm. The sensor’s transfer curves show the magnetoresistance (MR) variations as a function of MNP concentration. We demonstrate the detection capability of MNP amounts of below 500 ng and low MNP concentrations of 0.01, 0.1, and 1 mg/ml in solvents. This result suggests that the combination of high-sensitivity TMR sensors and large MNPs has a substantial potential for biomarker detection applications.
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Research context

OpenAlex topics: Magnetic properties of thin films · Characterization and Applications of Magnetic Nanoparticles · Physics of Superconductivity and Magnetism

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

Affiliations

Department of Applied Physics, Tohoku University 1 , Sendai 980-8579, Japan

Department of Materials Science and Engineering, Korea University 2 , Seoul 02841, Republic of Korea

Institute for High Technology Materials and Devices, Korea University 3 , Seoul 02841, Republic of Korea

Center for Science and Innovation in Spintronics (Core Research Cluster), Organization for Advanced Studies, Tohoku University 4 , Sendai 980-8577, Japan

Center for Spintronics Research Network, Tohoku University 5 , Sendai 980-8577, Japan

Funding

Center for Science and Innovation in Spintronics · Center for Innovative Integrated Electronic System · Korea Evaluation Institute of Industrial Technology · National Research Foundation of Korea · Strategic Promotion of Innovative R and D · Center for Spintronics Research Network, Tohoku University

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