Modulation of Photocurrent in Zinc-Based Metal Oxides Through Adjustment of a Magnetic Field and Localized Heating

摘要

We observe the modulation of photocurrent through a magnetic field in Sm2ZnO4 and Cd2ZnO4 micro-films. For better understanding the working principles, three quantitative models are derived to explain the magneto-photocurrent phenomena: (i) spin state transitions; (ii) magnetically controllable charge distribution; (iii) the interaction and coupling between polarization and magnetization. First, we employ spin state transitions to calculate the spin polarization that establishes the relation between the magnetic field and the photocurrent. Then, by utilizing a force balance equation and the Maxwell equations, the charge density dependence in the magnetic field is calculated, which accounts for the photocurrent dependence in the magnetic field. Finally, we report a free energy model to derive the dependence of electric polarization in the magnetic field. Based on the interaction between the magnetic field and polarization, the relation between the magnetic field and photocurrent is decoupled. We also observe variation of photocurrent in these metal oxides films along the thickness direction when a laser is used to heat the lateral sides at different positions. The phenomenon can be explained as the modulation of the depletion-layer depth.