TY - JOUR
T1 - Investigation of magnetic sensor properties of magnetic tunnel junctions with superparamagnetic free layer at low frequencies for biomedical imaging applications
AU - Ishikawa, Kyohei
AU - Oogane, Mikihiko
AU - Fujiwara, Kousuke
AU - Jono, Junichi
AU - Tsuchida, Masaaki
AU - Ando, Yasuo
N1 - Publisher Copyright:
© 2016 The Japan Society of Applied Physics.
PY - 2016/12
Y1 - 2016/12
N2 - 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.
AB - 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.
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U2 - 10.7567/JJAP.55.123001
DO - 10.7567/JJAP.55.123001
M3 - Article
AN - SCOPUS:84999664661
VL - 55
JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes
SN - 0021-4922
IS - 12
M1 - 123001
ER -