Coupling Effect of Magnetic Fields on Piezotronic and Piezophototronic Properties of ZnO and ZnO/Co₃O₄ Core/Shell Nanowire Arrays

Piezoelectric-related multiproperty coupling effects have recently attracted much attention for developing next generation multifunctional devices. In this paper, the multiproperty coupling effects among magnetic field, piezoelectricity, and photoexcitation were investigated in ZnO nanowire arrays. The response of the current flowing through the array to the applied magnetic field decreased with increasing magnetic field strength. However, due to piezo-magnetotronic effect, the magnetically induced current was magnified by 1 order of magnitude by applying an external stress. In contrast, under UV light illumination, the magnetically induced current response increased with an increment of magnetic field strength, as the magnetic field is favorable to the separation of photoinduced electron–hole pairs. The magnetically induced current response was enhanced by at least 2 orders of magnitude due to the piezo-photomagnetotronic effect. Furthermore, ZnO/Co3O4 core/shell heterojunction nanowire arrays were employed to improve the current responses up to 9 times and 3 times under piezo-magnetotronic and piezo-photomagnetotronic engagements, respectively, attributed to the improved charge carrier separation and transportation at the core/shell interface. This phenomenon projects a potential for multifunctional piezo-magnetotronic and piezo-photomagnetotronic device development.