A pT/√Hz sensitivity ac magnetic field sensor based on magnetoelectric composites using low-loss piezoelectric single crystals

•Magnetic sensors are designed using self-biased magnetoelectric composites made of piezoelectric PMN-PZT single crystals and magnetostrictive Ni.•A greatly enhanced magnetic sensitivity in the range of pT/√Hz is obtained from the ME composite based sensor, which is better than that of commercial magnetic sensors.•The loss factor of the piezoelectric layer is an important parameter affecting the magnetic field sensitivity.

This study reports of an ac magnetic field sensor with pT/√Hz sensitivity based on self-biased magnetoelectric composites made using piezoelectric Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 (PMN-PZT) single crystals in macro-fiber form and a magnetostrictive Ni plate. Variation in the loss properties of the PMN-PZT single crystals resulted in a substantial change in the magnetic field sensitivity of the ME based sensors. It was found that the loss factor of the piezoelectric layer was one of the key parameters affecting the magnetic field sensitivity. The ME composite sensor structure employing low-loss piezoelectric single crystals achieved a limit of detection (LOD) in the range of a few pT/√Hz at its resonance frequency (500 Hz). This magnitude of sensitivity is much higher than that offered bycommercially available magnetic sensors based on the giant magnetoresistance (GMR) effect or Hall-effect.