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Main Authors: Ying, Xuzhe, Law, K. T.
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2407.00325
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author Ying, Xuzhe
Law, K. T.
author_facet Ying, Xuzhe
Law, K. T.
contents We discuss the excitons in flat band systems. Quantum metric plays a central role in determining the properties of single exciton excitation as well as the exciton condensate. While the electrons and holes are extremely heavy in flat bands, the excitons (boundstate of an electron-hole pair) could be light and mobile. In particular, we show that the inverse of exciton's effective mass tensor is proportional to the quantum metric tensor. Meanwhile, the flat band excitons have a finite size, lower bounded by the trace of the quantum metric tensor. Given the properties of single exciton excitation, one can argue for the formation of exciton condensate. Because of the quantum metric, the exciton condensate can support dissipationless counterflow supercurrent, implying the stability of exciton condensate.
format Preprint
id arxiv_https___arxiv_org_abs_2407_00325
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Flat band excitons and quantum metric
Ying, Xuzhe
Law, K. T.
Mesoscale and Nanoscale Physics
We discuss the excitons in flat band systems. Quantum metric plays a central role in determining the properties of single exciton excitation as well as the exciton condensate. While the electrons and holes are extremely heavy in flat bands, the excitons (boundstate of an electron-hole pair) could be light and mobile. In particular, we show that the inverse of exciton's effective mass tensor is proportional to the quantum metric tensor. Meanwhile, the flat band excitons have a finite size, lower bounded by the trace of the quantum metric tensor. Given the properties of single exciton excitation, one can argue for the formation of exciton condensate. Because of the quantum metric, the exciton condensate can support dissipationless counterflow supercurrent, implying the stability of exciton condensate.
title Flat band excitons and quantum metric
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2407.00325