Low-Frequency Resonant Magnetoelectric Effects in Layered Heterostructures Antiferromagnet-Piezoelectric

Magnetic field sensors using magnetoelectric (ME) effects in planar ferromagnetic-piezoelectric heterostructures convert a magnetic field into an output voltage. The parameters of ME sensors are determined by characteristics of the magnetic constituent. In this work, the low-frequency ME effects in heterostructures comprising a layer of antiferromagnetic hematite & alpha;-Fe2O3 crystal with easy-plane anisotropy and a piezoelectric layer are studied. The effects arise due to a combination of magnetostriction and piezoelectricity because of mechanical coupling of the layers. The field dependences of magnetization and magnetostriction of the hematite crystal are measured. The resonant ME effects in the hematite-piezopolymer and hematite-piezoceramic structures are studied. The strong coupling between magnetic and acoustic subsystems of hematite results in a tuning of the acoustic resonance frequency by the magnetic field. For the hematite layer, the frequency tuning was found to be similar to 37% with an increase in the bias field up to 600 Oe. For the hematite-PVDF heterostructure, the frequency tuning reached similar to 24% and the ME coefficient was 58 mV/(Oe & BULL;cm). For the hematite-piezoceramic heterostructure, the frequency tuning was similar to 4.4% and the ME coefficient 4.8 V/(Oe & BULL;cm). Efficient generation of the second voltage harmonic in the hematite-piezoceramic heterostructure was observed.

Automated summary

This study investigates the low-frequency magnetoelectric (ME) effects in heterostructures consisting of a layer of antiferromagnetic hematite & alpha;-Fe2O3 crystal with easy-plane anisotropy and a piezoelectric layer. The results show that the frequency tuning of the hematite crystal is linearly related to the increase in the bias field, reaching up to 37%. The frequency tuning of the hematite-PVDF heterostructure is 24% with a ME coefficient of 58 mV/(Oe & BULL;cm). The frequency tuning of the hematite-piezoceramic heterostructure is 4.4% with a ME coefficient of 4.8 V/(Oe & BULL;cm). Additionally, efficient generation of the second voltage harmonic is observed in the hematite-piezoceramic heterostructure.