Sub-pT magnetic field detection by tunnel magneto-resistive sensors

Mikihiko Oogane, Kosuke Fujiwara, Akitake Kanno, Takafumi Nakano, Hiroshi Wagatsuma, Tadashi Arimoto, Shigemi Mizukami, Seiji Kumagai, Hitoshi Matsuzaki, Nobukazu Nakasato, Yasuo Ando

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


We developed tunnel magneto-resistive (TMR) sensors based on magnetic tunnel junctions (MTJs) that are able to detect a weak, sub-pT, magnetic field at a low frequency. Small detectivities of 0.94 pT/Hz1/2 at 1 Hz and 0.05 pT/Hz1/2 at 1 kHz were achieved by lowering the resistance of MTJs and enhancement of the signal using a thick CoFeSiB layer and magnetic flux concentrators. We demonstrated real-time measurement of magnetocardiography (MCG) and nuclear magnetic resonance (NMR) of protons using developed sensors. This result shows that both MCG and NMR can be measured by the same measurement system with ultra-sensitive TMR sensors.

Original languageEnglish
Article number123002
JournalApplied Physics Express
Issue number12
Publication statusPublished - 2021 Dec

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)


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