Pressure sensor based on magnetic tunnel junctions

Meyners, Dirk; Hofe, Thomas von; Vieth, M.; Rührig, M.; Schmitt, Stephan; Quandt, Eckhard

doi:10.1063/1.3063662

Cited by 46 publications

(27 citation statements)

References 12 publications

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“…Driven by the increasing demand for magnetic hard disk drives [42], magnetic tunneling junctions (MTJ) [43][44][45][46][47][48][49][50] are state-ofthe-art read-heads in magnetic hard drives. Additionally, they can be adapted for high strain sensitivity [51] and offer remarkable miniaturization opportunities [52]. In combination with already implemented processes of mass production, they are a promising alternative to piezoresistive and piezoelectric sensors for self-sensing AFM cantilevers [23].…”

Section: Magnetoresistive Strain Sensorsmentioning

confidence: 99%

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

Meier¹,

Förste²,

Tavassolizadeh³

et al. 2016

Nano Online

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We describe an atomic force microscope (AFM) for the characterization of self-sensing tunneling magnetoresistive (TMR) cantilevers. Furthermore, we achieve a large scan-range with a nested scanner design of two independent piezo scanners: a small high resolution scanner with a scan range of 5 × 5 × 5 μm 3 is mounted on a large-area scanner with a scan range of 800 × 800 × 35 μm 3. In order to characterize TMR sensors on AFM cantilevers as deflection sensors, the AFM is equipped with a laser beam deflection setup to measure the deflection of the cantilevers independently. The instrument is based on a commercial AFM controller and capable to perform large-area scanning directly without stitching of images. Images obtained on different samples such as calibration standard, optical grating, EPROM chip, self-assembled monolayers and atomic step-edges of gold demonstrate the high stability of the nested scanner design and the performance of self-sensing TMR cantilevers.

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Section: Magnetoresistive Strain Sensorsmentioning

confidence: 99%

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

Meier¹,

Förste²,

Tavassolizadeh³

et al. 2016

Nano Online

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show abstract

“…Recently, there are reports about strain‐gauge sensors based on spintronics technology that outperform conventional Si piezoresistive elements in strain sensitivity (gauge factor: GF). Such spintronic strain‐gauge sensors (spin‐SGSs) employ magnetic tunnel junction (MTJ) elements used in hard disk drive (HDD) read heads and magnetoresistive random access memory (MRAM) . MTJ elements are composed of two magnetic films—a sensing magnetic layer and a reference magnetic layer—separated by an insulator barrier layer.…”

Section: Introductionmentioning

confidence: 99%

“…Such spintronic straingauge sensors (spin-SGSs) employ magnetic tunnel junction (MTJ) elements used in hard disk drive (HDD) read heads and magnetoresistive random access memory (MRAM). [1][2][3][4] MTJ elements are composed of two magnetic films-a sensing magnetic layer and a reference magnetic layer-separated by an insulator barrier layer. MTJ elements used in HDD read heads can detect strength of external magnetic field through magnetoresistance effect (MR effect) when electric resistance changes with magnetization angle between the sensing layer with varied magnetization direction and the reference layer with fixed magnetization direction.…”

Section: Introductionmentioning

confidence: 99%

An ultrasensitive spintronic strain‐gauge sensor and a spin‐MEMS microphone

Fuji

Hara

Higashi

et al. 2018

Elect Comm in Japan

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This review provides the spintronic strain‐gauge sensor (Spin‐SGS) based on a magnetic tunnel junction (MTJ) with a high gauge factor in excess of 5000, which was realized by adopting a novel amorphous Fe‐B‐based sensing layer with high magnetostriction and low coercivity in a high magnetoresistance Mg‐O barrier MTJ. This review also provides a demonstration of novel “Spintronic MEMS (Spin‐MEMS) microphone,” in which a series of Spin‐SGSs are integrated onto a bulk micromachined diaphragm. The Spin‐MEMS microphone exhibits a signal‐to‐noise ratio (SNR) of 57 dB(A) due to the high strain sensitivity of the Spin‐SGSs.

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“…Profiting from high sensitivity [3], high band-width [4], and miniaturization possibilities, magnetostrictive magnetoresistance (MR) sensors are a promising alternative to piezoresistive and piezoelectric strain sensors. In particular, magnetostrictive TMR sensors with CoFeB/MgO/CoFeB structures [3,5,6] offer more scalability compared to magnetostrictive giant magnetoresistance sensors [7,8,9,10] and higher gauge factors compared to AlO x -based TMR sensors with amorphous CoFeB [11], crystalline Co 50 Fe 50 [12] and amorphous (Fe 90 Co 10 ) 78 Si 12 B 10 [13] electrodes. The CoFeB/MgO/CoFeB TMR sensors have been successfully incorporated into membranes for pressure sensing [5,14] and microcantilevers for atomic force microscopy (AFM) [6,15].…”

Section: Introductionmentioning

confidence: 99%

Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors

Tavassolizadeh

Rott

Meier

et al. 2016

Sensors

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Magnetostrictive tunnel magnetoresistance (TMR) sensors pose a bright perspective in micro- and nano-scale strain sensing technology. The behavior of TMR sensors under mechanical stress as well as their sensitivity to the applied stress depends on the magnetization configuration of magnetic tunnel junctions (MTJ)s with respect to the stress axis. Here, we propose a configuration resulting in an inverse effect on the tunnel resistance by tensile and compressive stresses. Numerical simulations, based on a modified Stoner–Wohlfarth (SW) model, are performed in order to understand the magnetization reversal of the sense layer and to find out the optimum bias magnetic field required for high strain sensitivity. At a bias field of −3.2 kA/m under a 0.2×10-3 strain, gauge factors of 2294 and −311 are calculated under tensile and compressive stresses, respectively. Modeling results are investigated experimentally on a round junction with a diameter of 30±0.2sans-serifμm using a four-point bending apparatus. The measured field and strain loops exhibit nearly the same trends as the calculated ones. Also, the gauge factors are in the same range. The junction exhibits gauge factors of 2150±30 and −260 for tensile and compressive stresses, respectively, under a −3.2 kA/m bias magnetic field. The agreement of the experimental and modeling results approves the proposed configuration for high sensitivity and ability to detect both tensile and compressive stresses by a single TMR sensor.

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Pressure sensor based on magnetic tunnel junctions

Cited by 46 publications

References 12 publications

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

A scanning probe microscope for magnetoresistive cantilevers utilizing a nested scanner design for large-area scans

An ultrasensitive spintronic strain‐gauge sensor and a spin‐MEMS microphone

Tunnel Magnetoresistance Sensors with Magnetostrictive Electrodes: Strain Sensors

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