TY  - JOUR
A1  - Krivenkov, Maxim
A1  - Marchenko, Dimitry
A1  - Sánchez-Barriga, Jaime
A1  - Golias, Evangelos
A1  - Rader, Oliver
A1  - Varykhalov, Andrei
T1  - Origin of the band gap in Bi-intercalated graphene on Ir(111)
T2  - 2D Materials
N2  - Proximity to heavy sp-elements is considered promising for reaching a band gap in graphene that could host quantum spin Hall states. The recent report of an induced spin-orbit gap of 0.2 eV in Pb-intercalated graphene detectable by spin-resolved photoemission has spurred renewed interest in such systems (Klimovskikh et al 2017 ACS Nano 11, 368). In the case of Bi intercalation an even larger band gap of 0.4 eV has been observed but was assigned to the influence of a dislocation network (Warmuth et al 2016 Phys. Rev. B 93, 165 437). Here, we study Bi intercalation under graphene on Ir(111) and report a nearly ideal graphene dispersion without band replicas and no indication of hybridization with the substrate. The band gap is small (0.19 eV) and can be tuned by +/- 25 meV through the Bi coverage. The Bi atomic density is higher than in the recent report. By spin-resolved photoemission we exclude induced spin-orbit interaction as origin of the gap. Quantitative agreement of a photoemission intensity analysis with the measured band gap suggests sublattice symmetry breaking as one of the possible band gap opening mechanisms. We test several Bi structures by density functional theory. Our results indicate the possibility that Bi intercalates in the phase of bismuthene forming a graphene-bismuthene van der Waals heterostructure.
KW  - graphene
KW  - bismuth
KW  - Ir(111)
KW  - spin-orbit interaction
KW  - ARPES
KW  - STM
KW  - bismuthene
Y1  - 2021
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/61373
SN  - 2053-1583
VL  - 8
IS  - 3
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  -