Hayes P, Jovičević Klug M, Toxværd S, Durdaut P, Schell V, Teplyuk A, Burdin D, Winkler A, Weser R, Fetisov Y, Höft M, Knöchel R, McCord J, Quandt E
Institute for Materials Science, Kiel University, Kiel, 24143, Germany.
Institute of Electrical and Information Engineering, Kiel University, Kiel, 24143, Germany.
Sci Rep. 2019 Nov 8;9(1):16355. doi: 10.1038/s41598-019-52657-w.
Magnetoelectric (ME) thin film composites consisting of sputtered piezoelectric (PE) and magnetostrictive (MS) layers enable for measurements of magnetic fields passively, i.e. an AC magnetic field directly generates an ME voltage by mechanical coupling of the MS deformation to the PE phase. In order to achieve high field sensitivities a magnetic bias field is necessary to operate at the maximum piezomagnetic coefficient of the MS phase, harnessing mechanical resonances further enhances this direct ME effect size. Despite being able to detect very small AC field amplitudes, exploiting mechanical resonances directly, implies a limitation to available signal bandwidth along with the inherent inability to detect DC or very low frequency magnetic fields. The presented work demonstrates converse ME modulation of thin film Si cantilever composites of mesoscopic dimensions (25 mm × 2.45 mm × 0.35 mm), employing piezoelectric AlN and magnetostrictive FeCoSiB films of 2 µm thickness each. A high frequency mechanical resonance at about 515 kHz leads to strong induced voltages in a surrounding pickup coil with matched self-resonance, leading to field sensitivities up to 64 kV/T. A DC limit of detection of 210 pT/Hz as well as about 70 pT/Hz at 10 Hz, without the need for a magnetic bias field, pave the way towards biomagnetic applications.
由溅射的压电(PE)层和磁致伸缩(MS)层组成的磁电(ME)薄膜复合材料能够被动地测量磁场,即交流磁场通过MS形变与PE相的机械耦合直接产生ME电压。为了实现高场灵敏度,需要一个磁偏置场来在MS相的最大压磁系数下工作,利用机械共振进一步增强这种直接ME效应的大小。尽管能够检测到非常小的交流场振幅,但直接利用机械共振意味着信号带宽有限,并且固有地无法检测直流或极低频磁场。本文展示了介观尺寸(25毫米×2.45毫米×0.35毫米)的薄膜硅悬臂梁复合材料的逆ME调制,该复合材料采用了厚度均为2微米的压电AlN和磁致伸缩FeCoSiB薄膜。约515kHz的高频机械共振在具有匹配自共振的周围拾波线圈中产生强感应电压,导致场灵敏度高达64kV/T。无需磁偏置场时,直流检测极限为210pT/Hz,在10Hz时约为70pT/Hz,为生物磁应用铺平了道路。