Absence of giant Rashba effect in the valence band of CsPbBr3
Maryam Sajedi a b, Maxim Krivenkov a b, Dmitry Marchenko a, Andrei Varykhalov a, Anoop Chandran c, Irene Aguilera c, Jaime Sanchez-Barriga a, Oliver Rader a b
a HELMHOLTZ - ZENTRUM BERLIN FUR MATERIALIEN UND ENERGIE GMBH
b Department of physics, Potsdam University, Am Neuen Palais 10, D-14415, Potsdam, Germany
c Institute of Energy and Climate Research IEK-5 Photovoltaics, 52425 Jülich, Germany
nanoGe Perovskite Conferences
Proceedings of International Conference on Perovskite Thin Film Photovoltaics and Perovskite Photonics and Optoelectronics (NIPHO20)
Sevilla, Spain, 2020 February 23rd - 25th
Organizer: Hernán Míguez
Oral, Maryam Sajedi, presentation 026
Publication date: 25th November 2019

We have employed spin- and angle-resolved photoemission spectroscopy of cesium lead tribromide (CsPbBr3) single crystal to verify the presence of Rashba spin-orbit coupling effect in the highest lying occupied state. We uncover the entire three-dimensional Brillouin zone momentum-space, and the dispersion of the topmost bulk valence band at high symmetry R-point. We use density functional theory (DFT) calculations to compare the ground state electronic structure of the particular perovskite compound with corresponding dispersive bands from photoemission experiments. In particular, using photoemission measurements with circularly polarized light, we elucidate direct evidence of circular dichroism from the uppermost valence band of CsPbBr3. The spin-resolved ARPES under the same conditions, however, does not show any spin splitting, thus we assign the dichroism effect to the final states with different characters of orbital angular momentum. By direct experimental evidence from the results of spin-resolved band structure experiments, we exclude a large Rashba effect in the global valence band maximum at R-point of bulk Brillouin zone.

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