Spin-Polarized Electrons Impact on Terahertz Emission by High-Order Shift Current in CsPbBr3

Ability to generate and manipulate spin-polarized electrons is the cornerstone of prospective energy-efficient spin-based information processing technologies. Here, we report a novel method of generating transient spin-polarized electrons by two-photon absorption (TPA) in all-inorganic perovskite CsPbBr3 using circularly polarized light (CPL) excitation. The photo-generated transient spin-polarized current serves as a source for terahertz emission detected in our experiment that shows quadratic pump fluence dependence, consistent with our previous report under linear polarized light excitation. Density functional calculations confirm the experimental results and pinpoint the role of the spin-orbit coupling in enabling TPA of CPL in CsPbBr3. In addition, the maximum degree of spin-polarization under excitation by the CPL is similar to 21.3% at room temperature and can be tuned by the polarization of the excitation light with a quarter wave plate. The technique developed in this work can be applied to the analysis of spin-related properties of materials, making it an important analytical tool for the exploration of future spintronic technology based on inorganic perovskites.