Extremely low equivalent magnetic noise in a Metglas/piezofiber magnetoelectric (ME) magetic‐field sensor, realized through a combination of a giant ME effect and a reduction in constituent internal noise sources, is demonstrated. The ME coefficient is 52 V cm−1 Oe−1 at low frequency, the 1 Hz equivalent magnetic noise is 5.1 pT Hz−1/2, and the magnetic field sensitivity is 10 nT.

). Das, J.; Gao, J.; Xing, Z.; et al., "Enhancement in the field sensitivity of magnetoelectric laminate heterostructures," Appl. Phys. Lett. 95, 092501 (2009); http:// dx

Since the turn of the millennium, multi-phase magnetoelectric (ME) composites have been subject to attention and development, and giant ME effects have been found in laminate composites of piezoelectric and magnetostrictive layers. From an application perspective, the practical usefulness of a magnetic sensor is determined not only by the output signal of the sensor in response to an incident magnetic field, but also by the equivalent magnetic noise generated in the absence of such an incident field. Here, a short review of developments in equivalent magnetic noise reduction for ME sensors is presented. This review focuses on internal noise, the analysis of the noise contributions and a summary of noise reduction strategies. Furthermore, external vibration noise is also discussed. The review concludes with an outlook on future possibilities and scientific challenges in the field of ME magnetic sensors.

We present a comparison of the magnetoelectric (ME) response and magnetic-field sensitivities of engineered laminate sensors comprised of magnetostrictive and piezoelectric phases. The ME voltage coefficients for Metglas and single crystal fibers of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) or Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN-PT) are about 2.8 times larger than those with Metglas-Pb(Zr,Ti)O3 (PZT) ceramic ones. This results in a 1.7 times enhancement in the magnetic-field sensitivity for the structures with single crystals. Accordingly, the noise floors are about three to four times lower for composites with PMN-PT or PZN-PT fibers than those with PZT.

High-resolution current sensor utilizing nanocrystalline alloy and magnetoelectric laminate composite Rev. Sci. Instrum. 83, 115001 (2012) A nonlinearity in the magnetoelectric coefficient, a 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 a 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 %5 Oe; whereas, for Metglas=PMN-PT, the maximum was found near zero dc bias. One application for a 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, a Nonlin ME has another application: removal of the necessity of a dc bias, which helps to design high-sensitivity sensor arrays and gradiometers.