Shift photovoltaic current and magnetically induced bulk photocurrent in piezoelectric sillenite crystals
A. Bürger, Lingyuan Gao, Radhe Agarwal, Alexey Aprelev, Jonathan E. Spanier, Andrew M. Rappe, V. M. Fridkin
Abstract
Recently, it has been shown how shift and ballistic currents in piezoelectric sillenite crystals ${\mathrm{Bi}}_{12}\mathrm{Ge}{\mathrm{O}}_{20}$ and ${\mathrm{Bi}}_{12}\mathrm{Si}{\mathrm{O}}_{20}$ can be separated experimentally under the assumption that the shift component of the circular current is small. However, it has been claimed that the shift and ballistic currents cannot be quantified by this method, due to the magnetophotovoltaic effect caused either by the change of the crystal's spatial symmetry in the magnetic field or by the breaking of time-reversal symmetry. Presently, we report observations of photovoltaic currents in ${\mathrm{Bi}}_{12}\mathrm{Si}{\mathrm{O}}_{20}$, excited by linearly and circularly polarized light under weak external magnetic field, as well as measurements of the corresponding photo-Hall signals. We demonstrate that the magnetophotovoltaic current constitutes a significant fraction of the measured current in the Hall direction for ${\mathrm{Bi}}_{12}\mathrm{Si}{\mathrm{O}}_{20}$ under specific experimental conditions.