Optical Excitations of Flat Bands Induced by Exciton Condensation in Ta$_2$Pd$_3$Te$_{5}$

Fuente: arXiv
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Autores principales: Yi, Shaohui, Liao, Zhiyu, Liang, Chenhao, Zhang, Sheng, Deng, Xiutong, Xie, Yongjie, Zheng, Lincong, Wang, Yujie, Wu, Yubiao, Wang, Zhijun, Shi, Youguo, Qiu, Xianggang, Xu, Bing
Formato: Preprint
Publicado: 2025
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author Yi, Shaohui
Liao, Zhiyu
Liang, Chenhao
Zhang, Sheng
Deng, Xiutong
Xie, Yongjie
Zheng, Lincong
Wang, Yujie
Wu, Yubiao
Wang, Zhijun
Shi, Youguo
Qiu, Xianggang
Xu, Bing
author_facet Yi, Shaohui
Liao, Zhiyu
Liang, Chenhao
Zhang, Sheng
Deng, Xiutong
Xie, Yongjie
Zheng, Lincong
Wang, Yujie
Wu, Yubiao
Wang, Zhijun
Shi, Youguo
Qiu, Xianggang
Xu, Bing
contents We report on the charge dynamics of Ta$_2$Pd$_3$Te$_5$ using temperature-dependent optical spectroscopy with polarized light. We observe a metal-insulator transition characterized by the collapse of Drude response and the emergence of sharp and narrow absorption peaks at low temperatures. Unlike previous excitonic insulator candidates such as TiSe$_2$ and Ta$_2$NiSe$_5$, where the excitonic order is intertwined with charge density wave or structural instabilities, the sharp features in Ta$_2$Pd$_3$Te$_5$ point to intrinsic excitonic excitations associated with ultra-flat bands driven by many-body renormalization of the band structure via spontaneous exciton condensation. Our findings thus provide clear-cut optical evidence for exciton condensation in a bulk crystal and establish Ta$_2$Pd$_3$Te$_5$ as a promising platform for exploring correlated quantum phases and novel excitonic phenomena.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18350
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optical Excitations of Flat Bands Induced by Exciton Condensation in Ta$_2$Pd$_3$Te$_{5}$
Yi, Shaohui
Liao, Zhiyu
Liang, Chenhao
Zhang, Sheng
Deng, Xiutong
Xie, Yongjie
Zheng, Lincong
Wang, Yujie
Wu, Yubiao
Wang, Zhijun
Shi, Youguo
Qiu, Xianggang
Xu, Bing
Materials Science
Strongly Correlated Electrons
We report on the charge dynamics of Ta$_2$Pd$_3$Te$_5$ using temperature-dependent optical spectroscopy with polarized light. We observe a metal-insulator transition characterized by the collapse of Drude response and the emergence of sharp and narrow absorption peaks at low temperatures. Unlike previous excitonic insulator candidates such as TiSe$_2$ and Ta$_2$NiSe$_5$, where the excitonic order is intertwined with charge density wave or structural instabilities, the sharp features in Ta$_2$Pd$_3$Te$_5$ point to intrinsic excitonic excitations associated with ultra-flat bands driven by many-body renormalization of the band structure via spontaneous exciton condensation. Our findings thus provide clear-cut optical evidence for exciton condensation in a bulk crystal and establish Ta$_2$Pd$_3$Te$_5$ as a promising platform for exploring correlated quantum phases and novel excitonic phenomena.
title Optical Excitations of Flat Bands Induced by Exciton Condensation in Ta$_2$Pd$_3$Te$_{5}$
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2506.18350