Design of magnetic concentrators for high sensitivity anisotropic magnetoresistor devices

Mansour, Malik; Coillot, Christophe; Chanteur, Gérard; Roux, A.; Dau, F. Nguyen Van

doi:10.1063/1.3337747

Cited by 7 publications

(4 citation statements)

References 4 publications

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“…According to the definition, the magnetic magnification of the MFC can be calculated by the ratio of the magnetic field in the MFC’s gap to the external magnetic field [14]. In our simulation, the magnetic field in the gap for both single and double gap MFC was computed by the average of the magnetic field in the gap’s middle area, with 3 μm width and 350 μm length, as marked by the green color in Figure 1c.…”

Section: Mfc Setup and Simulation Modelingmentioning

confidence: 99%

“…However, this type of sensor requires cryogenic refrigeration to operate, and the sensitivity is proportional to the superconducting flux area [10,11]. Magnetic flux concentrators (MFC) are another competitive method to improve the properties of MTJ sensors [12,13,14,15,16]. Firstly, it is easy to realize industrial production with low cost and low power consumption by using the mature integrated circuit technology, which benefits the miniaturization of the sensor system.…”

Section: Introductionmentioning

confidence: 99%

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Double-Gap Magnetic Flux Concentrator Design for High-Sensitivity Magnetic Tunnel Junction Sensors

Qiu

et al. 2019

Sensors

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To improve the sensitivity of the magnetic tunnel junction(MTJ)sensor, a novel architecture for a double-gap magnetic flux concentrator (MFC) was studied theoretically and experimentally in this paper. The three-dimensional finite element model of magnetic flux was established to optimize the magnetic field amplification factor, with different gaps. The simulation results indicate that the sensitivity of an MTJ sensor with a double-gap MFC can be significantly better than that of a sensor with a traditional single-gap MFC, due to the fact that the magnetic magnification sharply increases with the decrease in effective gap width. Besides this, the half-bridge MTJ sensors with the double-gap MFC were fabricated using photolithography, ion milling, evaporation, and electroplating processes. Experimental results show that the sensitivity of the MTJ sensor increased by ten times compared to the sensor without the double-gap MFC, which underlines the theoretical predictions. Furthermore, there is no significant increase in the sensor noise. The work in this paper contributes to the development of high-performance MTJ sensors.

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Section: Mfc Setup and Simulation Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Double-Gap Magnetic Flux Concentrator Design for High-Sensitivity Magnetic Tunnel Junction Sensors

Qiu

et al. 2019

Sensors

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“…It is reasonable to integrate the flux guides with GMR sensor via MEMS technologies. The sensitivity of magnetic sensors can be improved by several orders of magnitude by implementing them into especially tailored magnetic flux guides [3], [4], and the magnetic flux guides are well studied and widely used [5]- [8]. The GMR sensors are intrinsically sensitive to the magnetic field along the direction in-plane of the sensor substrate, and it is relatively easier to fabricate a magnetic sensor sensing the in-plane magnetic components.…”

Section: Introductionmentioning

confidence: 99%

Designs of Novel Magnetic Flux Guides for Three-Axis Magnetic Sensor

Zhao

Pan

2015

IEEE Trans. Magn.

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In general, giant magnetoresistance (GMR) sensors are only sensitive to the magnetic field in the plane of the substrate due to fabrication restraints. Then, a three-axis magnetic sensor based on GMR sensors has to be assembled to obtain three magnetic field components. Novel magnetic flux guides for three-axis magnetic sensor are described in this paper. These novel flux guides are designed with flux conversion structure and are able to bring magnetic flux out-of-plane to in-plane. With these flux guides, the magnetic field perpendicular to the chip surface can be detected with the GMR sensors in-plane. Then, numerical simulations are performed to validate the designs, and optimizations are made to improve the flux guides' performance. Based on these works, a three-axis magnetic sensor based on the in-plane GMR sensors is proposed. Without assembling the z-axis sensor, the integrated three-axis magnetic sensor is expected to have better angular position. According to the designs, the flux guides can be deposited with good symmetry. Therefore, Wheatstone bridges are configured to deduce a differential voltage, only relative to a certain component of the magnetic field. In addition, the magnetic field at the active region of the GMR sensor would be intensified. In addition, the sensitivity of the sensor can be improved due to the amplification ability of the flux guides.

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“…2 When the external magnetic field is removed, a nonuniform vortex field is trapped in a superconductor. Trapping of the internal field inside a superconductor can be realized by using the following procedure: 3 apply an external magnetic field, H a , to a superconductor at different temperatures, which results in the penetration of vortices into the bulk of the superconductor. H a is subsequently reduced to zero and the vortex lines are trapped inside the sample.…”

mentioning

confidence: 99%

Temperature dependence of the vortex remanent state in high-Tcsuperconductors

Chow

Jung

et al. 2011

Phys. Rev. B

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Temperature and magnetic field dependence of the vortex penetration into a superconductor and the resulting trapped vortex field (the vortex remanent state) were investigated for Bi 2 Sr 2 CaCu 2 O 8+x (BSCCO) and YBa 2 Cu 3 O 6+x (YBCO) single crystals and BSCCO thin films. The experiments revealed changes in the pinning regime (the magnitude and magnetic relaxation) of the trapped vortex field with an increasing temperature. The trapped vortex field, obtained by applying a constant magnetic field, exhibits a maximum at a certain temperature, that separates the partial vortex penetration regime at low temperatures from the complete vortex penetration state at higher temperatures. The corresponding vortex remanent states in these two regimes are characterized by two distinctly different relaxations, the logarithmic and the nonlogarithmic ones at temperatures below and above the maximum, respectively, for both BSCCO and YBCO. At temperatures close to T c surface/geometric barrier affect the relaxation rates. PACS number(s): 74.25. Op, 74.25.Uv, 74.25.Wx According to the Bean's model, 1 when an external magnetic field is applied to a superconductor, the internal magnetic field is not uniform and its local value depends on the position inside a superconductor. 2 When the external magnetic field is removed, a nonuniform vortex field is trapped in a superconductor. Trapping of the internal field inside a superconductor can be realized by using the following procedure: 3 apply an external magnetic field, H a , to a superconductor at different temperatures, which results in the penetration of vortices into the bulk of the superconductor. H a is subsequently reduced to zero and the vortex lines are trapped inside the sample. At a fixed temperature, the trapped magnetic field increases with an increasing H a and finally reaches a saturated (remanent) value. 4 The remanent value of the trapped internal field is proportional to the critical current.However, applying the same constant H a at different temperatures leads to a different situation. In this case, the magnitude of the trapped internal field is determined by the dependence of the penetration and pinning of the vortices on temperature. At low temperatures, the sample is partly penetrated by the field and the internal field is trapped at the sample's edges. It is expected that the trapped internal field increases with an increasing temperature and at a certain temperature, fully penetrates the sample, i.e., reaches a maximum value at the sample's center. The question is, however, what is the magnitude and the temperature dependence of this field at higher temperatures? Does it follow the temperature dependence of the remanent critical state where the current density acquires the critical value J c , or does it have a different temperature dependence? What are the relaxation rates of this field at temperatures corresponding to the partial and complete vortex penetration states? Are they affected by the surface/geometrical barriers? What is their dependence on the ...

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Design of magnetic concentrators for high sensitivity anisotropic magnetoresistor devices

Cited by 7 publications

References 4 publications

Double-Gap Magnetic Flux Concentrator Design for High-Sensitivity Magnetic Tunnel Junction Sensors

Double-Gap Magnetic Flux Concentrator Design for High-Sensitivity Magnetic Tunnel Junction Sensors

Designs of Novel Magnetic Flux Guides for Three-Axis Magnetic Sensor

Temperature dependence of the vortex remanent state in high-Tcsuperconductors

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