Magnetoelectric Ferrite–Piezoelectric Heterostructure With Coil-Free Excitation for DC Magnetic Field Sensing

This letter describes a new planar multiferroic ferrite–piezoelectric heterostructure that implements the coil-free excitation of the direct magnetoelectric (ME) effect. The heterostructure contains a magnetostrictive nickel–zinc ferrite layer with a conducting electrode on its surface and a layer of piezoelectric lead zirconate-titanate, mechanically coupled to each other. The ME effect is excited by passing an alternating current with an amplitude of up to 100 mA through the electrode, which creates an excitation magnetic field in the ferrite layer. A bias dc magnetic field of 0–500 Oe is applied tangentially to the ferrite layer. The ME voltage coefficient of
α_E
≈ 42 V/(Oe·cm) is obtained at the acoustic resonance frequency of the heterostructure of 186 kHz. The sensitivity of the structure to the permanent magnetic field reaches 2.4 mV/Oe and depends on the excitation current and orientation of the bias field. Implementation of heterostructures with coil-free excitation makes it possible, reducing the size and power consumption and improving the electromagnetic compatibility of ME magnetic field sensors.