High Magnetic Field Sensitivity in Ferromagnetic-Ferroelectric Composite with High Mechanical Quality Factor

In this study, composite devices were fabricated using ferromagnetic FeSiB-based alloys (Metglas) and ferroelectric ceramics, and their magnetic field sensitivity was evaluated. Sintered 0.95Pb(Zr_0.52Ti_0.48)O₃-0.05Pb(Mn_1/3Sb_2/3)O₃ (PZT-PMS) ceramic exhibited a very dense microstructure with a large piezoelectric voltage coefficient (g₃₁ = -16.8 × 10^-3 VmN^-1) and mechanical quality factor (Q_m > 1600). Owing to these excellent electromechanical properties of the PZT-PMS, the laminate composite with a Metglas/PZT-PMS/Metglas sandwich structure exhibited large magnetoelectric voltage coefficients (α_ME) in both off-resonance and resonance modes. When the length-to-width aspect ratio (l/w) of the composite was controlled, α_ME slightly varied in the off-resonance mode, resulting in similar sensitivity values ranging from 129.9 to 146.81 VT^-1. Whereas in the resonance mode, the composite with small l/w exhibited a large reduction of α_ME and sensitivity values. When controlling the thickness of the PZT-PMS (t), the α_ME of the composite showed the largest value when t was the smallest in the off-resonance mode, while α_ME was the largest when t is the largest in the resonance mode. The control of t slightly affected the sensitivity in the off-resonance mode, however, higher sensitivity was obtained as t increased in the resonance mode. The results demonstrate that the sensitivity, varying with the dimensional control of the composite, is related to the mechanical loss of the sensor. The composite sensor with the PZT-PMS layer exhibited excellent magnetic field sensitivity of 1.49 × 10⁵ VT^-1 with a sub-nT sensing limit, indicating its potential for application in high-performance magnetoelectric sensor devices.