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The integer quantum anomalous Hall (QAH) effect is a lattice analog of the quantum Hall effect at zero magnetic field. This striking transport phenomenon occurs in electronic systems with topologically nontrivial bands and spontaneous…

We report on our theoretical investigations that point to the possibility of a fractional quantum Hall effect with partial spin polarization at $\nu=3/8$. The physics of the incompressible state proposed here involves p-wave pairing of…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 V. W. Scarola , J. K. Jain , E. H. Rezayi

In the fractional quantum Hall effect regime we measure diagonal ($\rho_{xx}$) and Hall ($\rho_{xy}$) magnetoresistivity tensor components of two-dimensional electron system (2DES) in gated GaAs/Al$_{x}$Ga$_{1-x}$As heterojunctions,…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 S. S. Murzin , S. I. Dorozhkin , G. E. Tsydynzhapov , V. N. Zverev

The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 B. Andrei Bernevig , Shou-Cheng Zhang

It has been well-known that topological phenomena with fractional excitations, i.e., the fractional quantum Hall effect (FQHE) \cite{Tsui1982} will emerge when electrons move in Landau levels. In this letter, we report the discovery of the…

Strongly Correlated Electrons · Physics 2011-07-13 D. N. Sheng , Zheng-Cheng Gu , Kai Sun , L. Sheng

The recent discovery of the 3D quantum Hall effect in $\mathrm{HfTe_5}$ has also revealed puzzling signatures of possible 3D fractionalization. Beyond the first plateau associated with the lowest Landau band, Hall conductivity exhibits a…

Mesoscale and Nanoscale Physics · Physics 2026-05-05 Jun-Hong Li , Yi-Yuan Chen , Peng-Lu Zhao , Hai-Zhou Lu , X. C. Xie

We investigate theoretically the fractional quantum Hall effect at half-filling in the lowest Landau level observed in asymmetric wide quantum wells. The asymmetry can be achieved by a potential bias applied between the two sides of the…

Mesoscale and Nanoscale Physics · Physics 2014-05-21 N. Thiebaut , M. O. Goerbig , N. Regnault

The past few years have produced major advances in our understanding of the quantum Hall effects---quantized and unquantized. Theories based on a mathematical transformation, where the electrons are replaced by a set of fermions interacting…

Condensed Matter · Physics 2007-05-23 Bertrand I. Halperin

An important development in the field of the fractional quantum Hall effect has been the proposal that the 5/2 state observed in the Landau level with orbital index $n = 1$ of two dimensional electrons in a GaAs quantum well originates from…

Mesoscale and Nanoscale Physics · Physics 2019-10-25 Youngwook Kim , Ajit C. Balram , Takashi Taniguchi , Kenji Watanabe , Jainendra K. Jain , Jurgen H. Smet

Unlike regular electron spin, the pseudospin degeneracy of Fermi points in graphene does not couple directly to magnetic field. Therefore, graphene provides a natural vehicle to observe the integral and fractional quantum Hall physics in an…

Strongly Correlated Electrons · Physics 2009-11-11 Csaba Toke , Paul E. Lammert , Jainendra K. Jain , Vincent H. Crespi

Fully taking into account of the honeycomb lattice structure, fractional quantum Hall states of graphene are considered by a pseudopotential projected into the n = 0 Landau band. By using a chirality as an internal degree of freedom, the…

Strongly Correlated Electrons · Physics 2018-05-16 Koji Kudo , Yasuhiro Hatsugai

When a gas of electrons is confined to two dimensions, application of a strong magnetic field may lead to startling phenomena such as emergence of electron pairing. According to a theory this manifests itself as appearance of the fractional…

Mesoscale and Nanoscale Physics · Physics 2008-11-21 H. Saarikoski , E. Tolo , A. Harju , E. Rasanen

The quantum Hall effect was originally observed in a two-dimensional electron gas forming Landau levels when exposed to a strong perpendicular magnetic field and was later generalized to Chern insulators without net magnetization. Here,…

Mesoscale and Nanoscale Physics · Physics 2025-11-04 Benjamin Michen , Jan Carl Budich

We investigated the behavior of fractional quantum Hall (FQH) states in a two-dimensional electron system with layer thickness and an in-plane magnetic field. Our comparisons across various filling factors within the first Landau level…

Strongly Correlated Electrons · Physics 2024-03-26 Dan Ye , Chen-Xin Jiang , Zi-Xiang Hu

Recent systematic measurements of the quantum well width dependence of the excitation gaps of fractional quantum Hall states in high mobility samples [Villegas Rosales {\it et al.}, Phys. Rev. Lett. {\bf 127}, 056801 (2021)] open the…

Strongly Correlated Electrons · Physics 2022-06-01 Tongzhou Zhao , Koji Kudo , W. N. Faugno , Ajit C. Balram , J. K. Jain

Since the ground-breaking discovery of the quantum Hall effect, half-quantized quantum Hall plateaus have been some of the most studied and sought-after states. Their importance stems not only from the fact that they transcend the composite…

We observe fractional quantum Hall effect (FQHE) at the even-denominator Landau level filling factor $\nu=1/2$ in two-dimensional hole systems confined to GaAs quantum wells of width 30 to 50 nm and having bilayer-like charge distributions.…

Mesoscale and Nanoscale Physics · Physics 2014-09-30 Yang Liu , A. L. Graninger , S. Hasdemir , M. Shayegan , L. N. Pfeiffer , K. W. West , K. W. Baldwin , R. Winkler

The fractional quantum Hall (FQH) effect arises from strong electron correlations in a quantising magnetic field, and features exotic emergent phenomena such as electron fractionalisation. Using the diagrammatic Monte Carlo approach with…

Strongly Correlated Electrons · Physics 2026-03-16 Ben Currie , Evgeny Kozik

In non-interacting systems, disorder can drive a trivial phase into a topological one. However little is known how to construct a fractional quantum Hall ground-state, a paradigmatic topologically ordered state, that exists both in…

Strongly Correlated Electrons · Physics 2025-09-04 Justin Schirmann , Peru d'Ornellas , Charles Stahl , Adolfo G. Grushin

In this Letter, we study topological flat bands with distinct features that deviate from conventional Landau level behavior. We show that even in the ideal quantum geometry limit, moire flat band systems can exhibit physical phenomena…

Strongly Correlated Electrons · Physics 2025-11-27 Siddhartha Sarkar , Xiaohan Wan , Ang-Kun Wu , Shi-Zeng Lin , Kai Sun