Tuning of MgO barrier magnetic tunnel junction bias current for picotesla magnetic field detection

Ferreira, Ricardo; Wiśniowski, P.; Freitas, P. P.; Langer, J.; Ocker, B.; Maaß, W.

doi:10.1063/1.2173636

Cited by 35 publications

(25 citation statements)

References 5 publications

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“…PCB-based fluxgates achieved low noise (24 ) and good temperature stability (20 nT in the C to C range), but the minimum size achievable with this technology is about 10 mm [39].…”

Section: A Miniature Fluxgatesmentioning

confidence: 99%

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Advances in Magnetic Field Sensors

2010

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Abstract-The most important milestone in the field of magnetic sensors was when AMR sensors started to replace Hall sensors in many applications where the greater sensitivity of AMRs was an advantage. GMR and SDT sensors finally found applications. We also review the development of miniaturization of fluxgate sensors and refer briefly to SQUIDs, resonant sensors, GMIs, and magnetomechanical sensors.

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“…PCB-based fluxgates achieved low noise (24 ) and good temperature stability (20 nT in the C to C range), but the minimum size achievable with this technology is about 10 mm [39].…”

Section: A Miniature Fluxgatesmentioning

confidence: 99%

“…GMR and SDT sensors have noise with cutoff frequency in the order of MHz, and the reported noise levels are quite high [24]. Picotesla-detection predictions are usually based only on thermal noise, and they did not take magnetic noise into account [25].…”

Section: Crossfield Errormentioning

confidence: 99%

Advances in Magnetic Field Sensors

2010

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“…With reports of magnetoresistance ratios of several hundred percent at room temperature, much work is presently focused on TMR sensors with the ambition to develop a magnetic field sensor with picotesla sensitivity [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Low-frequency noise in planar Hall effect bridge sensors

Persson¹,

Bejhed²,

Nguyen³

et al. 2011

Sensors and Actuators A: Physical

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The low-frequency characteristics of planar Hall effect bridge sensors are investigated as function of the sensor bias current and the applied magnetic field. The noise spectra reveal a Johnson-like spectrum at high frequencies, and a 1/f-like excess noise spectrum at lower frequencies, with a knee frequency of around 400 Hz. The 1/f-like excess noise can be described by the phenomenological Hooge equation with a Hooge parameter of γ H =0.016. The detectivity is shown to depend on the total length, width and thickness of the bridge branches. Increasing the total length by a factor of 10 improves the detectivity by a factor of 10 1/2 . Moreover, the detectivity is shown to depend on the amplitude of the applied magnetic field, revealing a magnetic origin to part of the 1/f noise.

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“…The technique may be useful for spatial localization (MRI), relaxometry, diffusometry, or spin labeling in chemical analysis (15). With anticipated future advances in AMR sensors and related solid-state technologies such as tunneling magnetoresistance (16), solid-state, chip-scale magnetometers may eventually reach the 0.01 G/ ͌ Hz sensitivity level at room temperature (17). Incorporation of built-in microfluidic channels at the chip level will allow the construction of dedicated lab-on-a-chip devices.…”

mentioning

confidence: 99%

Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor

Verpillat

Ledbetter²,

Xu³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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We report the detection of nuclear magnetic resonance (NMR) using an anisotropic magnetoresistive (AMR) sensor. A ''remotedetection'' arrangement was used in which protons in flowing water were prepolarized in the field of a superconducting NMR magnet, adiabatically inverted, and subsequently detected with an AMR sensor situated downstream from the magnet and the adiabatic inverter. AMR sensing is well suited for NMR detection in microfluidic ''lab-on-a-chip'' applications because the sensors are small, typically on the order of 10 m. An estimate of the sensitivity for an optimized system indicates that Ϸ6 ؋ 10 13 protons in a volume of 1,000 m 3 , prepolarized in a 10-kG magnetic field, can be detected with a signal-to-noise ratio of 3 in a 1-Hz bandwidth. This level of sensitivity is competitive with that demonstrated by microcoils in superconducting magnets and with the projected sensitivity of microfabricated atomic magnetometers.anisotropic magnetoresistance ͉ microfluidics ͉ NMR ͉ adiabatic fast passage T he three essential elements of a nuclear magnetic resonance (NMR) or magnetic resonance imaging (MRI) experimentnuclear spin polarization, encoding, and detection-can be spatially separated; this is referred to as ''remote detection'' of NMR or MRI (1). One important potential advantage of this approach is that encoding and detection can occur in a near-zero magnetic field; however, conventional inductive detection has poor sensitivity at low frequencies, necessitating the use of alternative techniques for detection. Superconducting quantuminterference device (SQUID) magnetometers (2) and alkalivapor atomic magnetometers (3, 4) have been used successfully for this purpose. Magnetoresistance of thin films is a promising technology for sensitive magnetometry in small packages (5), and hybrid sensors involving superconducting pickup loops and magnetoresistive sensors have recently reached sensitivities on the order of 10-100 pG/ ͌ Hz (6, 7), approaching the sensitivities demonstrated by SQUIDs or atomic magnetometers (8). At room temperature, sensitivities on the order of 0.1-1 G/ ͌ Hz have been achieved by using spin valves or magnetic tunnel junctions with an area of Ϸ100 m 2 (9). Here we report the use of anisotropic magnetoresistive (AMR) sensors, operating at room temperature, for a remote-NMR experiment. Such thinfilm magnetoresistive sensors may be particularly attractive for microfluidic applications because they are small and require neither cryogenics nor vapor-cell heating (in contrast to SQUIDs and atomic magnetometers, respectively).The experimental setup is shown in Fig. 1. Tap water, prepolarized by f lowing through a Bruker 17-T magnet, then f lows through an adiabatic inversion region where its polarization is periodically reversed, after which it f lows past an AMR detector. The adiabatic polarization inverter incorporates a set of coils in anti-Helmholtz configuration to supply a gradient of B z along the direction of the water f low. A second set of Helmholtz coils is used to apply a 5.5-...

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Tuning of MgO barrier magnetic tunnel junction bias current for picotesla magnetic field detection

Cited by 35 publications

References 5 publications

Advances in Magnetic Field Sensors

Advances in Magnetic Field Sensors

Low-frequency noise in planar Hall effect bridge sensors

Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor

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