Investigation of magnetic sensor properties of magnetic tunnel junctions with superparamagnetic free layer at low frequencies for biomedical imaging applications

• Kyohei Ishikawa

• Mikihiko Oogane

• Kousuke Fujiwara

• Junichi Jono

• Masaaki Tsuchida

• Yasuo Ando

抄録

The magnetic sensor properties of magnetic tunnel junctions (MTJs) with a superparamagnetic (SP) free layer were systematically investigated at low frequencies (<10 Hz). We prepared four varieties of MTJs with various SP properties by changing the annealing temperature. The temperature dependence of magnetoresistance curves and the signal/noise property at 285 K were evaluated. We found that the SP free layer has the advantage of detecting very small and low-frequency AC magnetic fields compared with a ferromagnetic free layer. The SP free layer strongly suppressed magnetic 1/ f noise at low frequencies and expressed a very linear response to a small magnetic field. The obtained properties in MTJs with the SP free layer are suitable for detecting biomagnetic fields. The detectivity was 111 nT at low frequencies (from 0.1 to 10 Hz), which is one of the highest values in single-MTJ sensors.

収録刊行物

• Japanese Journal of Applied Physics

  Japanese Journal of Applied Physics 55 (12), 123001-, 2016-11-11

  IOP Publishing

キーワード

• General Physics and Astronomy
• General Engineering

詳細情報

• CRID: 1360847874820982400
• NII論文ID: 210000147294
• DOI: 10.7567/jjap.55.123001
• ISSN: 13474065
• ISSN: 00214922
• ISSN: http://id.crossref.org/issn/13474065
• Web Site: http://stacks.iop.org/1347-4065/55/i=12/a=123001/pdf
• Web Site: http://stacks.iop.org/1347-4065/55/i=12/a=123001?key=crossref.331ecdf576ef4e8f68fc05e296af44cd
• Web Site: https://iopscience.iop.org/article/10.7567/JJAP.55.123001
• Web Site: https://iopscience.iop.org/article/10.7567/JJAP.55.123001/pdf
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