Hybrid magnetic tunnel junction-MEMS high frequency field modulator for 1/f noise suppression

Guedes, A., Patil, S.B. , Wisniowski, P., Chu, V., Conde, J.P. and Freitas, P.P. (2008) Hybrid magnetic tunnel junction-MEMS high frequency field modulator for 1/f noise suppression. IEEE Transactions on Magnetics, 44(11), pp. 2554-2557. (doi:10.1109/TMAG.2008.2003539)

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A dc to ac magnetic field transformer was developed using a magnetic tunnel junction (MTJ)/microelectromechanical system (MEMS) mixed device. A MEMS torsionator was fabricated with an incorporated magnetic flux guide, that when actuated by a gate electrode, modulates an external dc field into the same frequency of the micro-torsionator oscillation. Attached to it a MgO based MTJ was fabricated, performing the detection of the generated ac magnetic field. This dc to ac field transformation enables the detection of dc magnetic fields in the high frequency thermal noise regime, where the 1/f noise is typically two orders of magnitude lower. Measurements show the detection of a modulated field at 460 kHz, coming from the MEMS torsionator designed to exhibit high modulation efficiency. This efficiency was of 11%, i.e., 11% of the external dc field is modulated. As a result, from a MTJ exhibiting a noise of SV MTJ=4.4 nT/Hz1/2 at 460 kHz, this hybrid device enables a dc magnetic field detection of 40 nT/Hz1/2. This work acts as a major improvement to a previous one , mainly through the optimization of the MEMS magnetic field modulation efficiency.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Patil, Dr Samadhan
Authors: Guedes, A., Patil, S.B., Wisniowski, P., Chu, V., Conde, J.P., and Freitas, P.P.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:IEEE Transactions on Magnetics
ISSN (Online):1941-0069
Published Online:17 December 2008

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