Composition Gradient-Enabled Circular Photogalvanic Effect in Epitaxial CsPbBr_xCl_(3-x) Film

Inversion symmetry breaking could lead to the creation of Rashba-Dresselhauls magnetic field which plays the key role in spintronic devices. In this project, we propose and develop a composition gradient engineering approach that breaks inversion symmetry in inorganic halide perovskite with strong spin-orbit coupling. We synthesize epitaxial CsPbBr<i>_x</i>Cl_(3-<i>x</i>) with Br/Cl composition gradient by a two-step chemical vapor deposition (CVD) approach. Through optoelectronic measurements, we show the presence of circular photogalvanic effect (CPGE) evidencing a Rashba-like spin polarized band structure. By spatially resolved photoluminescence spectra, we find that the observed CPGE is likely a cumulative result of inversion symmetry-broken interfaces featured by abrupt and stepwise composition gradient between the pristine and separated daughter phases. Our work suggests an avenue in engineering the spintronic property of halide perovskite for information processing.