Emergent flat band electronic structure in a VSe2/Bi2Se3 heterostructure

Turgut Yilmaz,Zhongwei Dai,Xiao Tong,Kenya Shimada,Konstantine Kaznatcheev,Boris Sinkovic,Jerzy T Sadowski,Eike F Schwier,Sooyeon Hwang,Kim Kisslinger,Elio Vescovo

doi:10.1038/s43246-020-00115-w

Turgut Yilmaz, Zhongwei Dai + Show 9 more

Open Access

https://doi.org/10.1038/s43246-020-00115-w

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Abstract

Flat band electronic states are proposed to be a fundamental tool to achieve various quantum states of matter at higher temperatures due to the enhanced electronic correlations. However, materials with such peculiar electronic states are rare and often rely on subtle properties of the band structures. Here, by using angle-resolved photoemission spectroscopy, we show the emergent flat band in a VSe2 / Bi2Se3 heterostructure. Our photoemission study demonstrates that the flat band covers the entire Brillouin zone and exhibits 2D nature with a complex circular dichroism. In addition, the Dirac cone of Bi2Se3 is not reshaped by the flat band even though they overlap in proximity of the Dirac point. These features make this flat band distinguishable from the ones previously found. Thereby, the observation of a flat band in the VSe2 / Bi2Se3 heterostructure opens a promising pathway to realize strongly correlated quantum effects in topological materials.

Highlights

Flat band electronic states are proposed to be a fundamental tool to achieve various quantum states of matter at higher temperatures due to the enhanced electronic correlations
We investigate the surface electronic structure of VSe2 transition metal dichalcogenides (TMDs) grown on the surface of Bi2Se3 topological insulator (TI) and show the emergence of a flat band in the electronic states
Another notable observation is that the VSe2 overlayer and the emergence of the flat band do not reshape the Dirac cone of Bi2Se3 in the vicinity of the Dirac point (DP) unlike the case of transition metal doping which opens a large gap at the DP18

Summary

Introduction

Flat band electronic states are proposed to be a fundamental tool to achieve various quantum states of matter at higher temperatures due to the enhanced electronic correlations. We investigate the surface electronic structure of VSe2 TMD grown on the surface of Bi2Se3 topological insulator (TI) and show the emergence of a flat band in the electronic states. Circular dichroism ARPES (CD-ARPES) measurements reveal that the CD signal of the flat band reverses the sign at several points within the BZ Another notable observation is that the VSe2 overlayer and the emergence of the flat band do not reshape the Dirac cone of Bi2Se3 in the vicinity of the Dirac point (DP) unlike the case of transition metal doping which opens a large gap at the DP18. Our results demonstrate a rich physics in this system and suggest a large family of materials as possible emergent flat bands and will motivate future studies based on heterostructure formed by other quantum materials such as superconductors

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