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Browsing by Author "Sing, M. Lam Chok"

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    Magnetoelectric nonlinearity in magnetoelectric laminate sensors
    Shen, Liangguo; Li, Menghui; Gao, Junqi; Shen, Ying; Li, Jiefang; Viehland, Dwight D.; Zhuang, Xin; Sing, M. Lam Chok; Cordier, Christophe; Saez, Sebastien; Dolabdjian, Christophe (American Institute of Physics, 2011-12-01)
    A nonlinearity in the magnetoelectric coefficient, alpha(Nonlin)(ME), of Metglas/Pb(Zr,Ti)O(3) (PZT) and Metglas/Pb(Mg(1/3),Nb(2/3))O(3)-PbTiO(3) (PMN-PT) laminate sensors has been observed. This nonlinearity was found to be dependent on the dc magnetic bias (H(dc)) and frequency of the ac drive field (H(ac)). The maximum value of alpha(Nonlin)(ME) for both types of composites was found near the electromechanical resonance. For Metglas/PZT laminates, the maximum occurred under a finite bias of H(dc) approximate to 5 Oe; whereas, for Metglas/PMN-PT, the maximum was found near zero dc bias. One application for alpha(Nonlin)(ME) is a cross-modulation scheme that can shift low frequency signals to higher frequency to achieve lower noise floor. For Metglas/PMN-PT, alpha(Nonlin)(ME) has another application: removal of the necessity of a dc bias, which helps to design high-sensitivity sensor arrays and gradiometers. (C) 2011 American Institute of Physics. [doi:10.1063/1.3665130]
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    Theoretical analysis of the intrinsic magnetic noise spectral density of magnetostrictive-piezoelectric laminated composites
    Zhuang, Xin; Cordier, Christophe; Saez, Sebastien; Sing, M. Lam Chok; Dolabdjian, Christophe; Gao, Junqi; Li, Jiefang; Viehland, Dwight D. (American Institute of Physics, 2011-06-15)
    The equivalent magnetic noise spectral density level for long type magnetostrictive-piezoelectric laminated composites has been investigated by using a 1D equivalent circuit model, and exemplified for a longitudinal-transverse mode. The theoretical developments explain well our experimental results. The findings show that similar ultimate magnetic noise spectral noise density can be expected whether using either charge or voltage amplifier detection methods. The findings show that a volume effect and the dielectric loss factor of the piezoelectric layer are the dominant sources of the noise floor. Our findings show that the noise scales as 1/root f. The lowest equivalent noise floor value that has been observed is 10/root f pT/root Hz for f << 10 kHz, with a white noise level of 100 fT/root Hz above 10 kHz. (C) 2011 American Institute of Physics. [doi:10.1063/1.3594714]