Dresden 2017 – wissenschaftliches Programm
CPP 20.6: Vortrag
Dienstag, 21. März 2017, 11:15–11:30, ZEU 222
Giant Rashba Splitting in (CH3NH3)PbBr3 Organic-Inorganic Perovskite — Daniel Niesner1, Max Wilhelm1, Ievgen Levchuk2, Andres Osvet2, Shreetu Shrestha2, Miroslaw Batentschuk2, Christoph Brabec2, 3, and •Thomas Fauster1 — 1Lehrstuhl für Festkörperphysik, FAU Erlangen-Nürnberg, Staudtstr. 7, D-91058 Erlangen, Germany — 2I-MEET, Department of Materials Science and Engineering, FAU Erlangen-Nürnberg, Martensstr. 7, D-91058 Erlangen, Germany — 3ZAE Bayern, Haberstr. 2a, D-91058 Erlangen, Germany
A Rashba-type spin-split band structure has been predicted for organic-inorganic perovskite semiconductors. The effect has been proposed as one of the origins of the exceptionally long carrier lifetimes in the materials, forming the basis of their successful application in optoelectronics. Using angle-resolved photoelectron spectroscopy, we investigate the band structure of (CH3NH3)PbBr3 single crystals cleaved in ultrahigh vacuum. The orthorhombic low-temperature phase and the cubic room-temperature phase are studied. We apply a modified leading-edge method to identify the dispersion of the valence band edge. It reveals two valence band maxima, separated in k-space by 0.043 Å−1. The dispersion is indicative of Rashba splitting. This interpretation is supported by the observation of circular dichroism in the orthorhombic phase. Extracted Rashba parameters of αo=7± 1 eV Å and αc=11± 4 eV Å in the orthorhombic and the cubic phase are amongst the largest reported to date.