Improved Magnetic Tunnel Junctions Design for the Detection of Superficial Defects by Eddy Currents Testing

Cardoso, Fabbryccio A. C. M.; Rosado, Luís S.; Franco, Fernando; Ferreira, Ricardo; Paz, Elvira; Cardoso, Susana; Ramos, Pedro M.; Piedade, M.S.; Freitas, P. P.

doi:10.1109/tmag.2014.2326959

Cited by 19 publications

(6 citation statements)

References 12 publications

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“…Major improvements were achieved upon the inclusion of crystalline MgO barriers and textured MTJ stacks. TMR values up to ∼600% were reported at room temperature for simple CoFeB/ MgO/CoFeB structures [38], and optimum values decrease to ∼250% for complex engineered stacks developed for device applications [9,[39][40][41][42]. The reported high TMR values are a consequence of coherent spin polarized tunneling.…”

Section: Tunnel Magnetoresistancementioning

confidence: 94%

Linearization strategies for high sensitivity magnetoresistive sensors

Silva

Leitao

Valadeiro

et al. 2015

Eur. Phys. J. Appl. Phys.

102

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Abstract. Ultrasensitive magnetic field sensors envisaged for applications on biomedical imaging require the detection of low-intensity and low-frequency signals. Therefore linear magnetic sensors with enhanced sensitivity low noise levels and improved field detection at low operating frequencies are necessary. Suitable devices can be designed using magnetoresistive sensors, with room temperature operation, adjustable detected field range, CMOS compatibility and cost-effective production. The advent of spintronics set the path to the technological revolution boosted by the storage industry, in particular by the development of read heads using magnetoresistive devices. New multilayered structures were engineered to yield devices with linear output. We present a detailed study of the key factors influencing MR sensor performance (materials, geometries and layout strategies) with focus on different linearization strategies available. Furthermore strategies to improve sensor detection levels are also addressed with best reported values of ∼40 pT/ √ Hz at 30 Hz, representing a step forward the low field detection at room temperature.

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Section: Tunnel Magnetoresistancementioning

confidence: 94%

Linearization strategies for high sensitivity magnetoresistive sensors

Silva

Leitao

Valadeiro

et al. 2015

Eur. Phys. J. Appl. Phys.

102

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“…120 A biorthogonal rectangular probe was developed by Zhang et al 52 Simulation results showed the new biorthogonal rectangular probe has a lesser effect on the lift-off with higher sensitivity detection. Meanwhile, Cardoso et al 121 optimized the sensor configuration in the eddy current probe design. A finite element modeling simulation was used to measure the accuracy detection of the probe design.…”

Section: Optimization Of Ect Probes Designmentioning

confidence: 99%

Challenges in improving the performance of eddy current testing: Review

Abdalla

Faraj

Samsuri

et al. 2018

Measurement and Control

124

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Eddy current testing plays an important role in numerous industries, particularly in material coating, nuclear and oil and gas. However, the eddy current testing technique still needs to focus on the details of probe structure and its application. This paper presents an overview of eddy current testing technique and the probe structure design factors that affect the accuracy of crack detection. The first part focuses on the development of different types of eddy current testing probes and their advantages and disadvantages. A review of previous studies that examined testing samples, eddy current testing probe structures and a review of factors contributing to eddy current signals is also presented. The second part mainly comprised an in-depth discussion of the lift-off effect with particular consideration of ensuring that defects are correctly measured, and the eddy current testing probes are optimized. Finally, a comprehensive review of previous studies on the application of intelligent eddy current testing crack detection in non destructive eddy current testing is presented.

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“…This study was done with two different sensors configuration and their validation was done by experimental and analytical studies of a CoCrPt thin film patterned array. 7 Two different sensors were used: 1) Sensor #1 (S1) composed of 72 MTJs structures with a single area of 50x50 µm 2 , connected in series and disposed in a 9x8 matrix (500x500 µm 2 ) to maximize the signal to noise ratio (SNR); 8 2) Sensor #2 (S2) consists on one line of 4 MTJs with single area of 10x4 µm 2 , connected in series with in a total spatial area of 59x4 µm 2 , which is expected to have more accuracy on the reading distance (RD); a schematic drawing of both sensors configuration are presented in Figure 1(a). After processing, an optimized sequence of two consecutive annealing steps at different temperatures for each AFM layer (each IrMn has different blocking temperature due to the different thicknesses) were performed to set the free layer perpendicularly to the pinned layer and achieve a linear response.…”

Section: All Article Content Except Where Otherwise Noted Is Licensmentioning

confidence: 99%

Reading magnetic ink patterns with magnetoresistive sensors

et al. 2018

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Information storage and monitoring relies on sensitive transducers with high robustness and reliability. This paper shows a methodology enabling the qualification of magnetic sensors for magnetic pattern readout, in applications different than hard disk magnetic recording. A magnetic tunnel junction MTJ sensor was incorporated in a reader setup for recognition of the magnetization of patterned arrays made of CoCrPt thin films and magnetic ink. The geometry of the sensor (in particular, the footprint and vertical distance to the media) was evaluated for two sensor configurations. The readout conditions were optimized to cope for variable media field intensity, resulting from CoCrPt film or magnetic ink thickness, with fixed reading distance and dimensions of the pattern. The calibration of the ink magnetic signal could be inferred from the analytical calculations carried out to validate the CoCrPt results.

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Improved Magnetic Tunnel Junctions Design for the Detection of Superficial Defects by Eddy Currents Testing

Cited by 19 publications

References 12 publications

Linearization strategies for high sensitivity magnetoresistive sensors

Linearization strategies for high sensitivity magnetoresistive sensors

Challenges in improving the performance of eddy current testing: Review

Reading magnetic ink patterns with magnetoresistive sensors

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