CC BY-NC-ND 4.0 UnportedSotome, M.Nakamura, M.Fujioka, J.Ogino, M.Kaneko, Y.Morimoto, T.Zhang, Y.Kawasaki, M.Nagaosa, N.Tokura, Y.Ogawa, N.2020-07-182020-07-182019https://doi.org/10.34657/3636https://oa.tib.eu/renate/handle/123456789/5007Photoexcitation 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.enghttps://creativecommons.org/licenses/by-nc-nd/4.0/530Bulk matterFerroelectricityPhotovoltaic effectPicosecond techniquesSolar cellsantimony derivativeantimony sulfur iodideiodine derivativesulfur derivativeunclassified drugArticledynamicselectric currentelectromagnetic radiationelectron transportfactor analysisferroelectric semiconductormathematical computingphotonpriority journalterahertz radiationArticle