1. Spectral dynamics of shift current in ferroelectric semiconductor SbSI.
- Author
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Sotome, M., Kaneko, Y., Nakamura, M., Ogawa, N., Kawasaki, M., Nagaosa, N., Tokura, Y., Fujioka, J., Ogino, M., Morimoto, T., and Zhang, Y.
- Subjects
FERROELECTRIC semiconductors ,PHOTOEXCITATION ,ELECTRONIC band structure ,PHOTOCURRENTS ,FERROELECTRICITY ,GEOMETRIC quantum phases - Abstract
Photoexcitation in solids brings about transitions of electrons/holes between different electronic bands. If the solid lacks an inversion symmetry, these electronic transitions support spontaneous photocurrent due to the geometric phase of the constituting electronic bands: the Berry connection. This photocurrent, termed shift current, is expected to emerge on the timescale of primary photoexcitation process. We observe ultrafast evolution of the shift current in a prototypical ferroelectric semiconductor antimony sulfur iodide (SbSI) by detecting emitted terahertz electromagnetic waves. By sweeping the excitation photon energy across the bandgap, ultrafast electron dynamics as a source of terahertz emission abruptly changes its nature, reflecting a contribution of Berry connection on interband optical transition. The shift excitation carries a net charge flow and is followed by a swing over of the electron cloud on a subpicosecond timescale. Understanding these substantive characters of the shift current with the help of first-principles calculation will pave the way for its application to ultrafast sensors and solar cells. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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