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Browsing by Author "Gray, David"

Now showing 1 - 6 of 6
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    Dependence of magnetic field sensitivity of a magnetoelectric laminate sensor pair on separation distance: Effect of mutual inductance
    Li, Menghui; Wang, Yaojin; Gao, Junqi; Gray, David; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2012-02-01)
    The effect of mutual inductance on the performance of a pair of Metglas/Pb(Zr,Ti)O-3 laminate magnetoelectric (ME) sensors has been studied. The effective value of the ME coefficient (alpha(ME)) for the laminates was reduced when the distance between was < 40 mm. Separating the two laminates by distances of > 40 mm, the effect of mutual inductance was small. The laminates exhibited the maximum values of alpha(ME). The ME sensor unit with two laminates connected in parallel had higher magnetic field sensitivities. 2012 American Institute of Physics. [doi:10.1063/1.3684986]
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    Enhanced dc magnetic field sensitivity by improved flux concentration in magnetoelectric laminates
    Gao, Junqi; Gray, David; Shen, Ying; Li, Jiefang; Viehland, Dwight D. (AIP Publishing, 2011-10-01)
    In this letter, we present magnetostatic modeling results that show significant magnetic field concentration tunability through geometric modification of high-mu tnagnetostatic Metglas layers of laminate magnetoelectric (ME) sensors. Based on the modeling results, composite ME sensors were fabricated with longer Metglas foils and found to exhibit notably higher ME voltage coefficients at smaller DC magnetic biases in response to a 1 kHz driving signal. Such ME sensors have been used to detect DC magnetic field changes as small as 6 nT at 1 kHz, while maintaining a signal-to-noise ratio greater than 10. This represents an enhancement of similar to 250% relative to values previously reported for Metglas/Pb(Zr,Ti)O(3) laminates. (C) 2011 American Institute of Physics. [doi:10.1063/1.3650713]
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    Enhanced sensitivity to direct current magnetic field changes in Metglas/Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) laminates
    Gao, Junqi; Shen, Liangguo; Wang, Yaojin; Gray, David; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2011-04-01)
    We have developed Metglas/Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) magnetoelectric (ME) laminates that have notably larger ME coefficients, with maximum values of up to 45 V/cm Oe. Based on this giant ME effect, the dc magnetic field sensitivity for Metglas/PMN-PT laminate sensors was improved by a factor of > 3, relative to that for Metglas/Pb(Zr,Ti)O(3) (PZT)-based ones of the same geometry. Our new ME sensor can detect dc magnetic field changes as small as (i) 5 nT at 1 kHz and (ii) 1 nT near the resonant frequency in a shield chamber. (C) 2011 American Institute of Physics. [doi:10.1063/1.3569629]
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    Enhancement in magnetic field sensitivity and reduction in equivalent magnetic noise by magnetoelectric laminate stacks
    Li, Menghui; Gao, Junqi; Wang, Yaojin; Gray, David; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2012-05-15)
    We have investigated the equivalent magnetic noise and magnetic field sensitivity for a magnetoelectric (ME) sensor unit of N numbers of ME laminates stacked together. Our results show with increasing N that the modeled and measured equivalent magnetic noises decreased by a factor of root N and that the magnetic field sensitivities increased by root N. For Metglas/Pb(Mg-1/3,Nb-2/3) O-3-PbTiO3 laminates, the equivalent magnetic noise decreased and the magnetic field sensitivity increased by a factors of 2.1 and 2.3, respectively, for N = 4 relative to that for N = 1. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4718441]
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    Enhancing the sensitivity of magnetoelectric sensors by increasing the operating frequency
    Petrie, Jonathan; Viehland, Dwight D.; Gray, David; Mandal, Sanjay; Sreenivasulu, Gollapudi; Srinivasan, Gopalan; Edelstein, Alan S. (American Institute of Physics, 2011-12-15)
    We present a field modulation technique that increases the operating frequency of magnetoelectric ( ME) sensors so that it can match the mechanical resonance frequency of the sensor. This not only improves the sensitivity but also reduces the effect of 1/f noise that is inherent at low frequencies. The technique, which is shown to apply to both symmetric and asymmetric ME sensors, relies on the strong, nonlinear magnetic field dependence of the magnetostriction. The combination of a lower 1/f noise and enhanced response at resonance has increased the signal to noise ratio of a symmetric sensor by two orders of magnitude. The detection limit of this sensor was lowered from 90 to 7 pT/root Hz at 1Hz in a magnetically unshielded environment. (C) 2011 American Institute of Physics. [doi:10.1063/1.3668752]
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    Shifting the operating frequency of magnetoelectric sensors
    Petrie, Jonathan; Gray, David; Viehland, Dwight D.; Sreenivasulu, Gollapudi; Srinivasan, Gopalan; Mandal, Sanjay; Edelstein, Alan S. (American Institute of Physics, 2012-04-01)
    A method is presented for increasing the operating frequency of symmetric and asymmetric magnetoelectric (ME) sensors so that the operating frequency can be equal to the mechanical resonance frequency of the sensor. This increase improves the signal to noise ratio of a symmetric sensor by at least two orders of magnitude because it mitigates the effect of 1/f noise and the sensor has an increased response at its resonant frequency. The method is based on the strong, nonlinear magnetic field dependence of the magnetostriction. Our method has lowered the detection limit to 4 pT/root Hz at 1 Hz in a magnetically unshielded environment. (C) 2012 American Institute of Physics. [doi:10.1063/1.3677840]