Possible Excitonic Insulating Phase in Quantum-Confined Sb Nanoflakes

In the 1960s, it was proposed that in small indirect band-gap materials, excitons can spontaneously form because the density of carriers is too low to screen the attractive Coulomb interaction between electrons and holes. The result is a novel strongly interacting insulating phase known as an excito...

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Bibliographic Details
Published in:Nano letters 2019-08, Vol.19 (8), p.4960-4964
Main Authors: Li, Zhi, Nadeem, Muhammad, Yue, Zengji, Cortie, David, Fuhrer, Michael, Wang, Xiaolin
Format: Article
Language:English
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Summary:In the 1960s, it was proposed that in small indirect band-gap materials, excitons can spontaneously form because the density of carriers is too low to screen the attractive Coulomb interaction between electrons and holes. The result is a novel strongly interacting insulating phase known as an excitonic insulator. Here we employ scanning tunnelling microscopy (STM) and spectroscopy (STS) to show that the enhanced Coulomb interaction in quantum-confined elemental Sb nanoflakes drives the system to the excitonic insulator state. The unique feature of the excitonic insulator, a charge density wave (CDW) without periodic lattice distortion, is directly observed. Furthermore, STS shows a gap induced by the CDW near the Fermi surface. Our observations suggest that the Sb(110) nanoflake is an excitonic insulator.
ISSN:1530-6984
1530-6992
DOI:10.1021/acs.nanolett.9b01123