Study On Ferromagnetic/Ferroelectric Heterostructure AC Magnetic Field Sensor With Zero Bias Magnetic Dielectric Effect

Magnetic sensor,designed for accuracy,sensitivity,and reliable measurements of external magnetic fields,plays an irreplaceable role for cutting-edge applications ranging from magnetometry,e-compass navigation/positioning to speed/angle detection.Among the mechanisms relied on by various magnetic sensors,magnetic dielectric effect has attracted widespread attention due to its passivity,higher signal-to-noise ratio and more stable signal output.However,due to the scarcity of natural magnetodielectric materials,harsh working temperature and low magnetodielectric coupling coefficient,sensitivity and magnetic field resolution still difficult to be further improved in magnetic sensors based on magnetodielectric effect.A dielectric AC magnetic sensor in layered ferrites/piezoelectric composites was fabricated and developed.The sensor was composed of three layers of terbium doped nickel-zinc ferrite magnetostrictive material and PZT piezoelectric ceramic.The significant magnetodielectric effects and typical magnetic=sensing characteristics in devices were systemically studied at room temperature,and beneficial attempts to further decrease the devices volume were performed at zero bias field without the sacrifice of sensitivity.Once the proposed device was subject to AC magnetic field,the sample will vibrate at exactly the same rate as the oscillating of driving sinusoidal input.In this case,the magnetodielectic interactions could be activated by strain-mediated inverse piezoelectric effects and eventually outputted in the form of capacitance.The giant magnetodielectric effect and typical magnetic-sensing parameters were systematically characterized at zero bias.Desired spinel structure and soft magnetic properties for solid-state sintering technique prepared ferrites with composition of Ni_0.7Zn_0.3Tb_0.02Fe_1.98O₄were confirmed by X-ray diffraction and VSM,respectively.Field-induced charge order insulating state in Ni_0.7Zn_0.3Tb_0.02Fe_1.98O₄ferrites accounts for the suppressed permittivity,which enables a possibility of highly sensitive magnetic sensor at zero bias field.Compared with the conventional ME-based solutions,high detecting sensitivity can be maintained without any external facilitations involved,and more stable signal with higher SNR for capacitance can be maintained relative to voltage.The advance of MDE strategy enables the utilization of ME bulk laminate with high-sensitivity magnetic-sensing possible,providing lots of design freedom and enriching the magnetic field detection solutions,magnetic material choices and giant MDE coupling strength account for the desired functions.