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Does Rashba splitting in CH3NH3PbBr3 arise from 2 × 2 surface reconstruction?
Xiaoyang Che1, Boubacar Traore, Claudine Katan
1Univ Rennes, ENSCR, INSA Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France. mikael.kepenekian@univ-rennes1.fr.
Investigating hybrid perovskite surfaces reveals a surface-induced Rashba effect, though smaller than previously reported. This suggests surface defects and polar domains influence spin-orbitronics applications.
Area of Science:
- Solid State Physics
- Materials Science
- Quantum Mechanics
Background:
- The Rashba-Dresselhaus effect in hybrid perovskites is crucial for spin-orbitronics.
- Experimental reports show a large Rashba splitting on the (001) surface of methylammonium lead bromide (CH3NH3PbBr3).
- This effect is absent in bulk CH3NH3PbBr3 due to its inversion symmetry.
Purpose of the Study:
- To investigate the electronic structure of two (001) nanoscale surface reconstructions of CH3NH3PbBr3.
- To understand the impact of methylammonium (MA) cation orientations on surface electronic properties.
- To reconcile theoretical predictions with experimental findings regarding the Rashba effect's amplitude.
Main Methods:
- First-principles calculations based on density functional theory (DFT).
- Analysis of electronic structures for zigzag and dimer surface reconstructions.
- Comparison of calculated Rashba splitting with experimental data.
Main Results:
- Calculations confirm the presence of a surface-induced Rashba effect in the reconstructed CH3NH3PbBr3 surfaces.
- The calculated Rashba splitting amplitude is significantly smaller than the experimentally reported value.
- The findings align with other experimental studies suggesting discrepancies.
Conclusions:
- The study indicates that nanoscale surface reconstructions alone do not fully explain the large experimentally observed Rashba splitting.
- Mesoscale surface polar domains and/or surface defects likely contribute to the discrepancy.
- Further research is needed to understand the role of sample preparation in Rashba effect magnitude for spin-orbitronics applications.
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