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Main Authors: Zhong, Jinrui, Peng, Huimin, Hu, Yuqing, Feng, Qi, Li, Qiuli, Zhang, Shihao, Wang, Qinsheng, Mao, Jinhai, Duan, Junxi, Yao, Yugui
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.05681
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author Zhong, Jinrui
Peng, Huimin
Hu, Yuqing
Feng, Qi
Li, Qiuli
Zhang, Shihao
Wang, Qinsheng
Mao, Jinhai
Duan, Junxi
Yao, Yugui
author_facet Zhong, Jinrui
Peng, Huimin
Hu, Yuqing
Feng, Qi
Li, Qiuli
Zhang, Shihao
Wang, Qinsheng
Mao, Jinhai
Duan, Junxi
Yao, Yugui
contents Due to the deep connection with the quantum geometry of electronic Bloch wavefunctions, the second-order nonlinear Hall effect (NLHE) has been an attractive topic since its proposal. However, studies on NLHE under a magnetic field have been lacking. Given that quantum oscillations in the linear response regime have been proven to be useful tools in investigating electronic systems, searching for quantum oscillations in NLHE is of great interest and is expected to provide new avenues to unveil rich quantum geometric properties of novel quasiparticles. Here, we propose a new type of NLHE quantum oscillations and experimentally probe it in graphene moiré systems. It stems from the alternation of the dominant NLHE mechanisms with recurring Bloch states under magnetic field, which enables sensitive detection of Brown-Zak fermions, giving an onset field as low as 0.5 T. Most importantly, when the commensurability condition is satisfied, the nonlinear transport of Brown-Zak fermions is mainly governed by quantum geometric contributions. Our findings not only establish a new type of quantum oscillations, but also demonstrate the first experimental detection of the topological nature of Brown-Zak fermions, shedding light on the exploration of novel topological quasiparticles.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05681
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Nonlinear Hall quantum oscillations to probe topological Brown-Zak fermions in graphene moiré systems
Zhong, Jinrui
Peng, Huimin
Hu, Yuqing
Feng, Qi
Li, Qiuli
Zhang, Shihao
Wang, Qinsheng
Mao, Jinhai
Duan, Junxi
Yao, Yugui
Mesoscale and Nanoscale Physics
Materials Science
Due to the deep connection with the quantum geometry of electronic Bloch wavefunctions, the second-order nonlinear Hall effect (NLHE) has been an attractive topic since its proposal. However, studies on NLHE under a magnetic field have been lacking. Given that quantum oscillations in the linear response regime have been proven to be useful tools in investigating electronic systems, searching for quantum oscillations in NLHE is of great interest and is expected to provide new avenues to unveil rich quantum geometric properties of novel quasiparticles. Here, we propose a new type of NLHE quantum oscillations and experimentally probe it in graphene moiré systems. It stems from the alternation of the dominant NLHE mechanisms with recurring Bloch states under magnetic field, which enables sensitive detection of Brown-Zak fermions, giving an onset field as low as 0.5 T. Most importantly, when the commensurability condition is satisfied, the nonlinear transport of Brown-Zak fermions is mainly governed by quantum geometric contributions. Our findings not only establish a new type of quantum oscillations, but also demonstrate the first experimental detection of the topological nature of Brown-Zak fermions, shedding light on the exploration of novel topological quasiparticles.
title Nonlinear Hall quantum oscillations to probe topological Brown-Zak fermions in graphene moiré systems
topic Mesoscale and Nanoscale Physics
Materials Science
url https://arxiv.org/abs/2605.05681