Low-Frequency Noise Characterization of CoFeB/MgO/CoFeB MTJ-Based Perpendicular Field Sensor

Bipul Das, Y. C. Lee, L. C. Li, Liu Yi-Shiou, Y. W. Suen, Lance Horng, Te Ho Wu, C. R. Chang, Jong-Ching Wu

Research output: Contribution to journalArticle

Abstract

We report low-frequency electrical resistance noise of Co 40 Fe 40 B 20 /MgO/Co 20 Fe 60 B 20 -based magnetic tunnel junction field sensors with reference and sensing layer magnetization directions along the out-of-plane and in-plane directions, respectively. The devices are fabricated using the sputter deposition and conventional lithography techniques with a short axis of ∼ 6 μ m long and long axes of ∼ 6-12 μm long. Noise power spectra under different bias currents indicate increase in noise power with increasing bias current. A close 1/f dependence of the noise according to Hooge's relation, S V (f)= AV 2 /f α (A is Hooge's like constant) is observed with an average value of α = 1.03.0.08. In smaller devices, the magnetic field dependence of noise amplitude follows similar trend of magnetoresistance (MR) behavior without any distinct peak near antiparallel-parallel states transition of the devices, which is generally observed for magnetic defects-induced resistance fluctuation. The experimental observations infer the resistance noises in those devices that are related to the defects associated with the spin independent charge trapping at structural defects near or in the barrier layer. The device with the smallest lateral size exhibits the Lorentzian contribution, whereas the device with the largest size shows magnetic contribution in total noise. Numerically deduced magnetic fluctuations Δ B rms of all the devices shows an average magnetic fluctuation of ∼ 10 nT except for one device. The devices show the highest MR% of ∼ 27 % under perpendicular magnetic field with a dynamic range of ∼ 25 Oe and a sensitivity of ∼ 0.3%/Oe. The observed low-frequency noise levels are suitable for the perpendicular field detection application and can be reduced more by improving the crystallinity of the device films stacks and their interfaces.

Original languageEnglish
Article number7428920
JournalIEEE Transactions on Magnetics
Volume52
Issue number7
DOIs
Publication statusPublished - 2016 Jul 1

Fingerprint

Bias currents
Magnetoresistance
Defects
Sensors
Magnetic fields
Charge trapping
Sputter deposition
Acoustic impedance
Tunnel junctions
Power spectrum
Lithography
Magnetization
Direction compound

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this

Das, Bipul ; Lee, Y. C. ; Li, L. C. ; Yi-Shiou, Liu ; Suen, Y. W. ; Horng, Lance ; Wu, Te Ho ; Chang, C. R. ; Wu, Jong-Ching. / Low-Frequency Noise Characterization of CoFeB/MgO/CoFeB MTJ-Based Perpendicular Field Sensor. In: IEEE Transactions on Magnetics. 2016 ; Vol. 52, No. 7.
@article{f90eed5fbdda4225bd9f1929b7f4735d,
title = "Low-Frequency Noise Characterization of CoFeB/MgO/CoFeB MTJ-Based Perpendicular Field Sensor",
abstract = "We report low-frequency electrical resistance noise of Co 40 Fe 40 B 20 /MgO/Co 20 Fe 60 B 20 -based magnetic tunnel junction field sensors with reference and sensing layer magnetization directions along the out-of-plane and in-plane directions, respectively. The devices are fabricated using the sputter deposition and conventional lithography techniques with a short axis of ∼ 6 μ m long and long axes of ∼ 6-12 μm long. Noise power spectra under different bias currents indicate increase in noise power with increasing bias current. A close 1/f dependence of the noise according to Hooge's relation, S V (f)= AV 2 /f α (A is Hooge's like constant) is observed with an average value of α = 1.03.0.08. In smaller devices, the magnetic field dependence of noise amplitude follows similar trend of magnetoresistance (MR) behavior without any distinct peak near antiparallel-parallel states transition of the devices, which is generally observed for magnetic defects-induced resistance fluctuation. The experimental observations infer the resistance noises in those devices that are related to the defects associated with the spin independent charge trapping at structural defects near or in the barrier layer. The device with the smallest lateral size exhibits the Lorentzian contribution, whereas the device with the largest size shows magnetic contribution in total noise. Numerically deduced magnetic fluctuations Δ B rms of all the devices shows an average magnetic fluctuation of ∼ 10 nT except for one device. The devices show the highest MR{\%} of ∼ 27 {\%} under perpendicular magnetic field with a dynamic range of ∼ 25 Oe and a sensitivity of ∼ 0.3{\%}/Oe. The observed low-frequency noise levels are suitable for the perpendicular field detection application and can be reduced more by improving the crystallinity of the device films stacks and their interfaces.",
author = "Bipul Das and Lee, {Y. C.} and Li, {L. C.} and Liu Yi-Shiou and Suen, {Y. W.} and Lance Horng and Wu, {Te Ho} and Chang, {C. R.} and Jong-Ching Wu",
year = "2016",
month = "7",
day = "1",
doi = "10.1109/TMAG.2016.2539422",
language = "English",
volume = "52",
journal = "IEEE Transactions on Magnetics",
issn = "0018-9464",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
number = "7",

}

Low-Frequency Noise Characterization of CoFeB/MgO/CoFeB MTJ-Based Perpendicular Field Sensor. / Das, Bipul; Lee, Y. C.; Li, L. C.; Yi-Shiou, Liu; Suen, Y. W.; Horng, Lance; Wu, Te Ho; Chang, C. R.; Wu, Jong-Ching.

In: IEEE Transactions on Magnetics, Vol. 52, No. 7, 7428920, 01.07.2016.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Low-Frequency Noise Characterization of CoFeB/MgO/CoFeB MTJ-Based Perpendicular Field Sensor

AU - Das, Bipul

AU - Lee, Y. C.

AU - Li, L. C.

AU - Yi-Shiou, Liu

AU - Suen, Y. W.

AU - Horng, Lance

AU - Wu, Te Ho

AU - Chang, C. R.

AU - Wu, Jong-Ching

PY - 2016/7/1

Y1 - 2016/7/1

N2 - We report low-frequency electrical resistance noise of Co 40 Fe 40 B 20 /MgO/Co 20 Fe 60 B 20 -based magnetic tunnel junction field sensors with reference and sensing layer magnetization directions along the out-of-plane and in-plane directions, respectively. The devices are fabricated using the sputter deposition and conventional lithography techniques with a short axis of ∼ 6 μ m long and long axes of ∼ 6-12 μm long. Noise power spectra under different bias currents indicate increase in noise power with increasing bias current. A close 1/f dependence of the noise according to Hooge's relation, S V (f)= AV 2 /f α (A is Hooge's like constant) is observed with an average value of α = 1.03.0.08. In smaller devices, the magnetic field dependence of noise amplitude follows similar trend of magnetoresistance (MR) behavior without any distinct peak near antiparallel-parallel states transition of the devices, which is generally observed for magnetic defects-induced resistance fluctuation. The experimental observations infer the resistance noises in those devices that are related to the defects associated with the spin independent charge trapping at structural defects near or in the barrier layer. The device with the smallest lateral size exhibits the Lorentzian contribution, whereas the device with the largest size shows magnetic contribution in total noise. Numerically deduced magnetic fluctuations Δ B rms of all the devices shows an average magnetic fluctuation of ∼ 10 nT except for one device. The devices show the highest MR% of ∼ 27 % under perpendicular magnetic field with a dynamic range of ∼ 25 Oe and a sensitivity of ∼ 0.3%/Oe. The observed low-frequency noise levels are suitable for the perpendicular field detection application and can be reduced more by improving the crystallinity of the device films stacks and their interfaces.

AB - We report low-frequency electrical resistance noise of Co 40 Fe 40 B 20 /MgO/Co 20 Fe 60 B 20 -based magnetic tunnel junction field sensors with reference and sensing layer magnetization directions along the out-of-plane and in-plane directions, respectively. The devices are fabricated using the sputter deposition and conventional lithography techniques with a short axis of ∼ 6 μ m long and long axes of ∼ 6-12 μm long. Noise power spectra under different bias currents indicate increase in noise power with increasing bias current. A close 1/f dependence of the noise according to Hooge's relation, S V (f)= AV 2 /f α (A is Hooge's like constant) is observed with an average value of α = 1.03.0.08. In smaller devices, the magnetic field dependence of noise amplitude follows similar trend of magnetoresistance (MR) behavior without any distinct peak near antiparallel-parallel states transition of the devices, which is generally observed for magnetic defects-induced resistance fluctuation. The experimental observations infer the resistance noises in those devices that are related to the defects associated with the spin independent charge trapping at structural defects near or in the barrier layer. The device with the smallest lateral size exhibits the Lorentzian contribution, whereas the device with the largest size shows magnetic contribution in total noise. Numerically deduced magnetic fluctuations Δ B rms of all the devices shows an average magnetic fluctuation of ∼ 10 nT except for one device. The devices show the highest MR% of ∼ 27 % under perpendicular magnetic field with a dynamic range of ∼ 25 Oe and a sensitivity of ∼ 0.3%/Oe. The observed low-frequency noise levels are suitable for the perpendicular field detection application and can be reduced more by improving the crystallinity of the device films stacks and their interfaces.

UR - http://www.scopus.com/inward/record.url?scp=84977071118&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84977071118&partnerID=8YFLogxK

U2 - 10.1109/TMAG.2016.2539422

DO - 10.1109/TMAG.2016.2539422

M3 - Article

VL - 52

JO - IEEE Transactions on Magnetics

JF - IEEE Transactions on Magnetics

SN - 0018-9464

IS - 7

M1 - 7428920

ER -