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Metrological investigations of the quantum Hall effect (QHE) completed by transport measurements at low magnetic field are carried out in a-few-$\mu\mathrm{m}$-wide Hall bars made of monolayer (ML) or bilayer (BL) exfoliated graphene…

Mesoscale and Nanoscale Physics · Physics 2013-08-26 J. Guignard , D. Leprat , D. C. Glattli , F. Schopfer , W. Poirier

We have studied the magnetic field dependence of the thermal conductivity $\kappa(T,B)$ of highly oriented pyrolytic graphite samples at temperatures 0.2K$ \le T < 10$K and fields 0T$ \le B \le 9$T. The samples show clear deviations from…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Konstantin Ulrich , Pablo Esquinazi

We study the \nu=5/2 even-denominator fractional quantum Hall effect (FQHE) over a wide range of magnetic (B) field in a heterojunction insulated gate field-effect transistor (HIGFET). The electron density can be tuned from n=0 to 7.6…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 W. Pan , H. L. Stormer , D. C. Tsui , L. N. Pfeiffer , K. W. Baldwin , K. W. West

We report observations of well developed half integer quantum Hall effect (QHE) on mono layer graphene films of 7 mm \times 7 mm in size. The graphene films are grown by chemical vapor deposition (CVD) on copper, then transferred to SiO_{2}…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Tian Shen , Wei Wu , Qingkai Yu , Curt A Richter , Randolph Elmquist , David Newell , Yong P. Chen

Highly dendritic graphene crystals up to 0.25 mm in diameter are synthesized by low pressure chemical vapor deposition inside a copper enclosure. With their sixfold symmetry and fractal-like shape, the crystals resemble snowflakes. The…

Materials Science · Physics 2013-01-30 Mathieu Massicotte , Victor Yu , Eric Whiteway , Dan Vatnik , Michael Hilke

We present temperature-dependent magneto-transport experiments around the charge neutrality point in graphene and determine the amplitude of potential fluctuations $s$ responsible for the formation of electron-hole puddles. The experimental…

The response of a graphene Hall-Effect sensor to the inhomogeneous magnetic field generated by a dipole located above it, is investigated numerically at room temperature as a function of the dipole position, its orientation and the…

Mesoscale and Nanoscale Physics · Physics 2024-10-07 Lionel Petit , Thomas Blon , Benjamin Lassagne

The quantum Hall effect is widely used for the investigation of fundamental phenomena, ranging from topological phases to composite fermions. In particular, the discovery of a room temperature resistance quantum in graphene is significant…

We have observed the well-kown quantum Hall effect (QHE) in epitaxial graphene grown on silicon carbide (SiC) by using, for the first time, only commercial NdFeB permanent magnets at low temperature. The relatively large and homogeneous…

Mesoscale and Nanoscale Physics · Physics 2017-08-22 F. D. Parmentier , T. Cazimajou , Y. Sekine , H. Hibino , H. Irie , D. C. Glattli , N. Kumada , P. Roulleau

We have measured the quantum-Hall activation gaps in graphene at filling factors $\nu=2$ and $\nu=6$ for magnetic fields up to 32 T and temperatures from 4 K to 300 K. The $\nu =6$ gap can be described by thermal excitation to broadened…

Mesoscale and Nanoscale Physics · Physics 2007-11-19 A. J. M. Giesbers , U. Zeitler , M. I. Katsnelson , L. A. Ponomarenko , T. M. G. Mohiuddin , J. C. Maan

The quantum anomalous Hall effect (QAHE) is a robust topological phenomenon featuring quantized Hall resistance at zero magnetic field. We report the QAHE in a rhombohedral pentalayer graphene/monolayer WS2 heterostructure. Distinct from…

Mesoscale and Nanoscale Physics · Physics 2024-05-14 Tonghang Han , Zhengguang Lu , Yuxuan Yao , Jixiang Yang , Junseok Seo , Chiho Yoon , Kenji Watanabe , Takashi Taniguchi , Liang Fu , Fan Zhang , Long Ju

The half-integer quantum Hall effect in epitaxial graphene is compared with high precision to the well known integer effect in a GaAs/AlGaAs heterostructure. We find no difference between the quantised resistance values within the relative…

Mesoscale and Nanoscale Physics · Physics 2012-05-01 T. J. B. M. Janssen , J. M. Williams , N. E. Fletcher , R. Goebel , A. Tzalenchuk , R. Yakimova , S. Lara-Avila , S. Kubatkin , V. I. Fal'ko

Measurements of the basal-plane resistivity rho_a(T,H) performed on highly oriented pyrolitic graphite, with magnetic field H parallel to the c-axis in the temperature interval 2 - 300 K and fields up to 8 T, provide evidence for the…

Strongly Correlated Electrons · Physics 2009-11-07 Y. Kopelevich , V. V. Lemanov , S. Moehlecke , J. H. S. Torres

The fractional quantum anomalous Hall effect (FQAHE), the analog of the fractional quantum Hall effect1 at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking. The…

Mesoscale and Nanoscale Physics · Physics 2023-12-29 Zhengguang Lu , Tonghang Han , Yuxuan Yao , Aidan P. Reddy , Jixiang Yang , Junseok Seo , Kenji Watanabe , Takashi Taniguchi , Liang Fu , Long Ju

The temperature dependence of the Hall coefficient of a series of ferromagnetic Ga(1-x)Mn(x)As samples is measured in the temperature range 80K < T < 500K. We model the Hall coefficient assuming a magnetic susceptibility given by the…

We report the observation of a quantum anomalous Hall effect in twisted bilayer graphene showing Hall resistance quantized to within .1\% of the von Klitzing constant $h/e^2$ at zero magnetic field.The effect is driven by intrinsic strong…

Strongly Correlated Electrons · Physics 2020-03-18 M. Serlin , C. L. Tschirhart , H. Polshyn , Y. Zhang , J. Zhu , K. Watanabe , T. Taniguchi , L. Balents , A. F. Young

Electrons in topological flat bands can form novel topological states driven by the correlation effects. The penta-layer rhombohedral graphene/hBN moire superlattice has been shown to host fractional quantum anomalous Hall effect (FQAHE) at…

Mesoscale and Nanoscale Physics · Physics 2024-08-20 Zhengguang Lu , Tonghang Han , Yuxuan Yao , Jixiang Yang , Junseok Seo , Lihan Shi , Shenyong Ye , Kenji Watanabe , Takashi Taniguchi , Long Ju

The quantum Hall effect, with a Berry's phase of $\pi$ is demonstrated here on a single graphene layer grown on the C-face of 4H silicon carbide. The mobility is $\sim$ 20,000 cm$^2$/V$\cdot$s at 4 K and ~15,000 cm$^2$/V$\cdot$s at 300 K…

Mesoscale and Nanoscale Physics · Physics 2009-12-08 Xiaosong Wu , Yike Hu , Ming Ruan , Nerasoa K Madiomanana , John Hankinson , Mike Sprinkle , Claire Berger , Walt A. de Heer

The phenomenon of fractional quantum Hall effect (FQHE) was first experimentally observed 33 years ago. FQHE involves strong Coulomb interactions and correlations among the electrons, which leads to quasiparticles with fractional elementary…

Mesoscale and Nanoscale Physics · Physics 2015-01-05 Xi Lin , Rui -Rui Du , Xincheng Xie

We report an experimental investigation of fractional quantum Hall effect (FQHE) at the even-denominator Landau level filling factor $\nu$ = 1/2 in very high quality wide GaAs quantum wells, and at very high magnetic fields up to 45 T. The…

Mesoscale and Nanoscale Physics · Physics 2013-12-24 J. Shabani , Y. Liu , M. Shayegan , L. N. Pfeiffer , K. W. West , K. W. Baldwin