2020/06/23 by Turgut Yilmaz, Tong Xiao, Yilmaz, Turgut +19
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Graphene research and applications #Materials Science (cond-mat.mtrl-sci) #Quantum and electron transport phenomena #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2006.13447
openalex publication_date 2020/06/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Dispersionless flat bands are proposed to be a fundamental ingredient to\nachieve the various sought after quantum states of matter including\nhigh-temperature superconductivity1-4 and fractional quantum Hall effect5-6.\nMaterials with such peculiar electronic states, however, are very rare and\noften exhibit very complex band structures. Here, we report on the emergence of\na flat band with a possible insulating ground state in the sub-monolayer VSe2 /\nBi2Se3 heterostructure by means of angle-resolved photoemission spectroscopy\nand scanning tunneling microscopy. The flat band is dispersionless along the\nkll and kz momenta, filling the entire Brillouin zone, and it exhibits a\ncomplex circular dichroism signal reversing the sign at several points of the\nBrillouin zone. These properties together with the presence of a Moir 'e\npatterns in VSe2 suggest that the flat band is not a trivial disorder or\nconfinement effect and could even be topologically non-trivial. Another\nintriguing finding is that the flat band does not modify the Dirac cone of\nBi2Se3 around the Dirac point. Furthermore, we found that the flat band and the\nDirac surface states of Bi2Se3 have opposite energy shifts with electron\ndoping. This opens a novel way of controlling the spin texture of photocurrents\nas well as the transport properties of the heterostructure. These features make\nthis flat band remarkably distinguishable from previous findings and our\nmethodology can be applied to other systems opening a promising pathway to\nrealize strongly correlated quantum effects in topological materials.\n