Dynamic symmetry breaking and spin splitting in metal halide perovskites

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Metal halide perovskites exhibit a materials physics that is distinct from traditional semiconductors. While materials such as CH3NH3PbI3 are nonmagnetic, the presence of heavy elements (Pb and I) in a noncentrosymmetric crystal environment result in a spin splitting of the frontier electronic bands through the Rashba-Dresselhaus effect. We show, from a combination of ab initio molecular dynamics, density-functional theory, and quasiparticle GW theory, that the nature (magnitude and orientation) of the band splitting depends on the local asymmetry around the Pb and I sites in the perovskite structure. The potential fluctuations vary in time as a result of thermal disorder. We show that the same physics emerges both for the organic-inorganic CH3NH3PbI3 and the inorganic CsPbI3 compound. The results are relevant to the photophysics of these compounds and are expected to be general to other lead iodide containing perovskites.

Original languageEnglish
Article number085108
JournalPhysical Review B
Issue number8
Publication statusPublished - 6 Aug 2018

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