Charge density wave in a band insulator

Fuente: arXiv
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Autori principali: Hossain, Md Shafayat, Liu, Wenhao, Zhang, Yuqi, Zhang, Qi, Lei, Chao, Shumiya, Nana, Dagnino, Kouta, Litskevich, Maksim, Jiang, Yu-Xiao, Yin, Jia-Xin, Dhale, Nikhil, Cheng, Zi-Jia, Kim, Byunghoon, Li, Yongkai, Cochran, Tyler A., Yang, Xian P., Zhang, Fan, Yao, Yugui, Wang, Zhiwei, Lv, Bing, Neupert, Titus, Balicas, Luis, Hasan, M. Zahid
Natura: Preprint
Pubblicazione: 2026
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author Hossain, Md Shafayat
Liu, Wenhao
Zhang, Yuqi
Zhang, Qi
Lei, Chao
Shumiya, Nana
Dagnino, Kouta
Litskevich, Maksim
Jiang, Yu-Xiao
Yin, Jia-Xin
Dhale, Nikhil
Cheng, Zi-Jia
Kim, Byunghoon
Li, Yongkai
Cochran, Tyler A.
Yang, Xian P.
Zhang, Fan
Yao, Yugui
Wang, Zhiwei
Lv, Bing
Neupert, Titus
Balicas, Luis
Hasan, M. Zahid
author_facet Hossain, Md Shafayat
Liu, Wenhao
Zhang, Yuqi
Zhang, Qi
Lei, Chao
Shumiya, Nana
Dagnino, Kouta
Litskevich, Maksim
Jiang, Yu-Xiao
Yin, Jia-Xin
Dhale, Nikhil
Cheng, Zi-Jia
Kim, Byunghoon
Li, Yongkai
Cochran, Tyler A.
Yang, Xian P.
Zhang, Fan
Yao, Yugui
Wang, Zhiwei
Lv, Bing
Neupert, Titus
Balicas, Luis
Hasan, M. Zahid
contents Charge density wave (CDW) implies a periodic modulation of the charge density. Typically observed in metallic systems, CDWs arise from Fermi surface instabilities, resulting in the total or partial gapping of the Fermi surface. Here, we present experimental evidence for a CDW state emerging in a band insulator which has no Fermi surface. The bulk and surface of our material platform, Bi4Br4, is gapped over the entire Brillouin zone. Through topographic and spectroscopic imaging at low temperatures, we unveil an unexpected unidirectional charge modulation in Bi4Br4, breaking the lattice translation symmetry. The CDW develops at temperatures below 40 K and adds an energy gap atop the existing insulating gap of Bi4Br4. Furthermore, our transport measurements reveal nonlinear electrical conduction, a phenomenon conventionally associated with the sliding or phason mode of incommensurate CDWs. These highly unusual observations represent a new type of CDW and demand a new theoretical framework for CDWs.
format Preprint
id arxiv_https___arxiv_org_abs_2605_24153
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Charge density wave in a band insulator
Hossain, Md Shafayat
Liu, Wenhao
Zhang, Yuqi
Zhang, Qi
Lei, Chao
Shumiya, Nana
Dagnino, Kouta
Litskevich, Maksim
Jiang, Yu-Xiao
Yin, Jia-Xin
Dhale, Nikhil
Cheng, Zi-Jia
Kim, Byunghoon
Li, Yongkai
Cochran, Tyler A.
Yang, Xian P.
Zhang, Fan
Yao, Yugui
Wang, Zhiwei
Lv, Bing
Neupert, Titus
Balicas, Luis
Hasan, M. Zahid
Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Materials Science
Applied Physics
Charge density wave (CDW) implies a periodic modulation of the charge density. Typically observed in metallic systems, CDWs arise from Fermi surface instabilities, resulting in the total or partial gapping of the Fermi surface. Here, we present experimental evidence for a CDW state emerging in a band insulator which has no Fermi surface. The bulk and surface of our material platform, Bi4Br4, is gapped over the entire Brillouin zone. Through topographic and spectroscopic imaging at low temperatures, we unveil an unexpected unidirectional charge modulation in Bi4Br4, breaking the lattice translation symmetry. The CDW develops at temperatures below 40 K and adds an energy gap atop the existing insulating gap of Bi4Br4. Furthermore, our transport measurements reveal nonlinear electrical conduction, a phenomenon conventionally associated with the sliding or phason mode of incommensurate CDWs. These highly unusual observations represent a new type of CDW and demand a new theoretical framework for CDWs.
title Charge density wave in a band insulator
topic Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Materials Science
Applied Physics
url https://arxiv.org/abs/2605.24153