Magnetoelectric laminate sensor system for pico-tesla magnetic field sensing

The magnetoelectric (ME) effect, with a cross-coupling between magnetic and electric orders, is associated with a promising application of magnetic field sensors. Compared with other magnetic field sensors, ME laminate sensors are compact, economic and power efficient with pico-Tesla sensitivity at low frequencies while operating at room temperature and can be used in many applications. However, the performance of ME laminate sensors is determined both by the output signal of the sensor and the equivalent magnetic noise level. Two ways are given to reduce the equivalent magnetic noise: enhancement of the ME coefficient and rejection of noise sources. The first way can be achieved by the selection of decent materials and optimization of fabrication techniques of ME laminates, and the second can be achieved by detection circuit optimization. The most appropriate piezoelectric material and magnetostrictive material for proposed ME sensor was selected to reduce the dielectric loss noise and increase the piezomagnetic coefficient. PZT-5A1 and Metglas VITROVAC 7600 T70 were employed as piezoelectric layer and magnetostrictive layer. As a result, the maximum ME coefficient of proposed laminate was 35 V/(cm∙Oe).