TY  - JOUR
A1  - Clark, Oliver J.
A1  - Freyse, Friedrich
A1  - Yashina, L. V.
A1  - Rader, Oliver
A1  - Sanchez-Barriga, Jaime
T1  - Robust behavior and spin-texture stability of the topological surface state in Bi2Se3 upon deposition of gold
JF  - npj quantum materials
N2  - The Dirac point of a topological surface state (TSS) is protected against gapping by time-reversal symmetry. Conventional wisdom stipulates, therefore, that only through magnetisation may a TSS become gapped. However, non-magnetic gaps have now been demonstrated in Bi2Se3 systems doped with Mn or In, explained by hybridisation of the Dirac cone with induced impurity resonances. Recent photoemission experiments suggest that an analogous mechanism applies even when Bi2Se3 is surface dosed with Au. Here, we perform a systematic spin- and angle-resolved photoemission study of Au-dosed Bi2Se3. Although there are experimental conditions wherein the TSS appears gapped due to unfavourable photoemission matrix elements, our photon-energy-dependent spectra unambiguously demonstrate the robustness of the Dirac cone against high Au coverage. We further show how the spin textures of the TSS and its accompanying surface resonances remain qualitatively unchanged following Au deposition, and discuss the mechanism underlying the suppression of the spectral weight.
KW  - Electronic properties and materials
KW  - Topological matter
Y1  - 2022
U6  - https://doi.org/10.1038/s41535-022-00443-9
SN  - 2397-4648
VL  - 7
IS  - 1
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Sajedi, Maryam
A1  - Krivenkov, Maxim
A1  - Marchenko, Dmitry
A1  - Sanchez-Barriga, Jaime
A1  - Chandran, Anoop K.
A1  - Varykhalov, Andrei
A1  - Rienks, Emile D. L.
A1  - Aguilera, Irene
A1  - Blügel, Stefan
A1  - Rader, Oliver
T1  - Is there a polaron signature in Angle-Resolved Photoemission of CsPbBr3?
JF  - Physical review letters
N2  - The formation of large polarons has been proposed as reason for the high defect tolerance, low mobility, low charge carrier trapping, and low nonradiative recombination rates of lead halide perovskites. Recently, direct evidence for large-polaron formation has been reported from a 50% effective mass enhancement in angle-resolved photoemission of CsPbBr3 over theory for the orthorhombic structure. We present in-depth band dispersion measurements of CsPbBr3 and GW calculations, which lead to similar effective masses at the valence band maximum of 0.203 1 0.016 m0 in experiment and 0.226 m0 in orthorhombic theory. We argue that the effective mass can be explained solely on the basis of electron-electron correlation and largepolaron formation cannot be concluded from photoemission data.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevLett.128.176405
SN  - 0031-9007
SN  - 1079-7114
VL  - 128
IS  - 17
PB  - American Physical Society
CY  - College Park
ER  -