Rashba Band Splitting in CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>: An Insight from Spin-Polarized Scanning Tunneling Spectroscopy.
basic_science · Level V
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- Record sourced from PubMed, PMID 31841346.
- Also identified by DOI 10.1021/acs.nanolett.9b03800.
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Abstract
We report an experimental observation of Rashba splitting in methylammonium lead iodide (MAPbI<sub>3</sub>). Because of a large spin-orbit coupling parameter in the noncentrosymmetric material, both of the bands were predicted to split having two different spin-textures leading to two different <i>Z</i>-components of total angular momentum (<i>J</i><sub><i>Z</i></sub>). We use spin-polarized scanning tunneling spectroscopy to probe only one-type of <i>J</i><sub><i>Z</i></sub>-matched bands throughout the film; d<i>I</i>/d<i>V</i> spectra recorded at many different points of a film however allowed us to spot both the Rashba split-levels and also deliberate on their spin-textures. We observe that the bands split in such a manner that the conduction and valence bands closer to the Fermi energy have the same type of spin-textures (a spin-allowed transition model). Still a low recombination rate of photogenerated carriers in MAPbI<sub>3</sub> has been analyzed by considering Wannier<b>-</b>type excitons, a molecular nature of spin-domains from d<i>I</i>/d<i>V</i> images, and therefore a spin-forbidden nature of interdomain transition.