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Non-Hermitian topology in the quantum Hall effect of graphene

Authors :
Özer, Burak
Ochkan, Kyrylo
Chaturvedi, Raghav
Maltsev, Evgenii
Könye, Viktor
Giraud, Romain
Veyrat, Arthur
Hankiewicz, Ewelina M.
Watanabe, Kenji
Taniguchi, Takashi
Büchner, Bernd
Brink, Jeroen van den
Fulga, Ion Cosma
Dufouleur, Joseph
Veyrat, Louis
Publication Year :
2024

Abstract

Quantum Hall phases have recently emerged as a platform to investigate non-Hermitian topology in condensed-matter systems. This platform is particularly interesting due to its tunability, which allows to modify the properties and topology of the investigated non-Hermitian phases by tuning external parameters of the system such as the magnetic field. Here, we show the tunability of non-Hermitian topology chirality in a graphene heterostructure using a gate voltage. By changing the charge carrier density, we unveil some novel properties specific to different quantum Hall regimes. First, we find that the best quantization of the non-Hermitian topological invariant is interestingly obtained at very high filling factor rather than on well-quantized quantum Hall plateaus. This is of particular importance for the efficient operation of devices based on non-Hermitian topology. Moreover, we observe an additional non-Hermitian topological phase in the insulating nu=0 quantum Hall plateau, which survives at lower fields than the opening of the nu=0 gap, confirming a recent prediction of a disorder-induced trivial phase. Our results evidence graphene as a promising platform for the study of non-Hermitian physics and of emergent phases in such topological devices.

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2410.14329
Document Type :
Working Paper