TY - JOUR
T1 - Detection of small magnetic fields using serial magnetic tunnel junctions with various geometrical characteristics
AU - Jin, Zhenhu
AU - Wang, Yupeng
AU - Fujiwara, Kosuke
AU - Oogane, Mikihiko
AU - Ando, Yasuo
N1 - Funding Information:
authors have read and agreed to the published version of the manuscript. sensor measurement. Z.J. analyzed the data. K.F., Y.A., and M.O. read and commented on the manuscript. All Funding: The work was supported by the S-Innovation program, the Japan Science and Technology Agency (JST, authors have read and agreed to the published version of the manuscript. 201106007), the Center for Innovative Integrated Electronic System (CIES), the Center for Spintronics Research Funding: The work was supported by the S-Innovation program, the Japan Science and Technology Agency Co(JnSfTli,c t2s0o11f0I6n0te0r7e),s tt:hTehCeeanuttehro rfosrd eInclnaorevantoivceonInfltiecgtroaftiendt eErelesct.tronic System (CIES), the Center for Spintronics Research Network (CSRN), and the Organization for Advanced Studies, Center for Science and Innovation in ReSfpeinretrnocneicss.
Funding Information:
The work was supported by the S-Innovation program, the Japan Science and Technology Agency (JST, authors have read and agreed to the published version of the manuscript. 201106007), the Center for Innovative Integrated Electronic System (CIES), the Center for Spintronics Research Network Funding: (CSRN), The work and the was Organization supported by for the Advanced S-Innovation Studies, program, Center the for Science Japan Science and Innovation and Technology in Spintronics.
PY - 2020/10/1
Y1 - 2020/10/1
N2 - Thanks to their high magnetoresistance and integration capability, magnetic tunnel junction-based magnetoresistive sensors are widely utilized to detect weak, low-frequency magnetic fields in a variety of applications. The low detectivity of MTJs is necessary to obtain a high signal-to-noise ratio when detecting small variations in magnetic fields. We fabricated serial MTJ-based sensors with various junction area and free-layer electrode aspect ratios. Our investigation showed that their sensitivity and noise power are affected by the MTJ geometry due to the variation in the magnetic shape anisotropy. Their MR curves demonstrated a decrease in sensitivity with an increase in the aspect ratio of the free-layer electrode, and their noise properties showed that MTJs with larger junction areas exhibit lower noise spectral density in the low-frequency region. All of the sensors were able detect a small AC magnetic field (Hrms = 0.3 Oe at 23 Hz). Among the MTJ sensors we examined, the sensor with a square-free layer and large junction area exhibited a high signal-to-noise ratio (4792 ± 646). These results suggest that MTJ geometrical characteristics play a critical role in enhancing the detectivity of MTJ-based sensors.
AB - Thanks to their high magnetoresistance and integration capability, magnetic tunnel junction-based magnetoresistive sensors are widely utilized to detect weak, low-frequency magnetic fields in a variety of applications. The low detectivity of MTJs is necessary to obtain a high signal-to-noise ratio when detecting small variations in magnetic fields. We fabricated serial MTJ-based sensors with various junction area and free-layer electrode aspect ratios. Our investigation showed that their sensitivity and noise power are affected by the MTJ geometry due to the variation in the magnetic shape anisotropy. Their MR curves demonstrated a decrease in sensitivity with an increase in the aspect ratio of the free-layer electrode, and their noise properties showed that MTJs with larger junction areas exhibit lower noise spectral density in the low-frequency region. All of the sensors were able detect a small AC magnetic field (Hrms = 0.3 Oe at 23 Hz). Among the MTJ sensors we examined, the sensor with a square-free layer and large junction area exhibited a high signal-to-noise ratio (4792 ± 646). These results suggest that MTJ geometrical characteristics play a critical role in enhancing the detectivity of MTJ-based sensors.
KW - Integrated magnetic sensor
KW - Magnetic tunnel junction
KW - Magnetoresistance sensor
KW - Tunnel magnetoresistance
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U2 - 10.3390/s20195704
DO - 10.3390/s20195704
M3 - Letter
C2 - 33036470
AN - SCOPUS:85092364589
VL - 20
SP - 1
EP - 9
JO - Sensors (Switzerland)
JF - Sensors (Switzerland)
SN - 1424-8220
IS - 19
M1 - 5704
ER -