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We report on an experimental study of spin and valley blockade in two-electron bilayer graphene (BLG) double quantum dots (DQDs) and explore the limits set by asymmetric orbitals and electronelectron interactions. The results obtained from…

Trapping electrons in quantum dots and controlling their collective quantum states is crucial for converting semiconductor structures into bits of quantum information processing. Here, we study single- and two-particle states in quantum…

Mesoscale and Nanoscale Physics · Physics 2020-07-01 Angelika Knothe , Vladimir Fal'ko

Understanding how the electron spin is coupled to orbital degrees of freedom, such as a valley degree of freedom in solid-state systems is central to applications in spin-based electronics and quantum computation. Recent developments in the…

Artificial molecular states of double quantum dots defined in bilayer graphene are studied with the atomistic tight-binding and its low-energy continuum approximation. We indicate that the extended electron wave functions have opposite…

Mesoscale and Nanoscale Physics · Physics 2017-08-02 D. P. Żebrowski , F. M. Peeters , B. Szafran

Bilayer graphene (BLG) offers a rich platform for broken symmetry states stabilized by interactions. In this work we study the phase diagram of BLG in the quantum Hall regime at filling factor $\nu=0$ within the Hartree-Fock approximation.…

Strongly Correlated Electrons · Physics 2017-12-27 Ganpathy Murthy , Efrat Shimshoni , Herbert Fertig

The flat bands in bilayer graphene(BLG) are sensitive to electric fields E\bot directed between the layers, and magnify the electron-electron interaction effects, thus making BLG an attractive platform for new two-dimensional (2D) electron…

Mesoscale and Nanoscale Physics · Physics 2012-03-23 J. Velasco , L. Jing , W. Bao , Y. Lee , P. Kratz , V. Aji , M. Bockrath , C. N. Lau , C. Varma , R. Stillwell , D. Smirnov , Fan Zhang , J. Jung , A. H. MacDonald

By applying the infinite-mass boundary condition, we analytically calculate the confined states and the corresponding wave functions of AA-stacked bilayer graphene quantum {dots} in the presence of an uniform magnetic field $B$. It is found…

Mesoscale and Nanoscale Physics · Physics 2016-02-29 Abdelhadi Belouad , Youness Zahidi , Ahmed Jellal

Owing to the spin, valley, and orbital symmetries, the lowest Landau level (LL) in bilayer graphene exhibits multicomponent quantum Hall ferromagnetism. Using transport spectroscopy, we investigate the energy gaps of integer and fractional…

Mesoscale and Nanoscale Physics · Physics 2016-03-23 Yanmeng Shi , Yongjin Lee , Shi Che , Ziqi Pi , Timothy Espiritu , Petr Stepanov , Dmitry Smirnov , Chun Ning Lau , Fan Zhang

The intrinsic valley degree of freedom makes bilayer graphene (BLG) a unique platform for semiconductor qubits. The single-carrier quantum dot (QD) ground state exhibits a two-fold degeneracy, where the two states that constitute a Kramers…

We report on ground- and excited state transport through an electrostatically defined few-hole quantum dot in bilayer graphene in both parallel and perpendicular applied magnetic fields. A remarkably clear level scheme for the two-particle…

Mesoscale and Nanoscale Physics · Physics 2019-07-17 A. Kurzmann , M. Eich , H. Overweg , M. Mangold , F. Herman , P. Rickhaus , R. Pisoni , Y. Lee , R. Garreis , C. Tong , K. Watanabe , T. Taniguchi , K. Ensslin , T. Ihn

Electron and hole Bloch states in gapped bilayer graphene exhibit topological orbital magnetic moments with opposite signs near the band edges, which allows for tunable valley-polarization in an out-of-plane magnetic field. This intrinsic…

Despite various novel broken symmetry states have been revealed in bilayer graphene (BLG) experimentally, the atomic-scale spectroscopic investigation has been greatly limited. Here, we study high-resolution spectroscopic characteristics of…

Mesoscale and Nanoscale Physics · Physics 2020-04-29 Long-Jing Yin , Li-Juan Shi , Li-Zhen Yang , Ling-Hui Tong , Lin He

We study the orbital effect of a strong magnetic field parallel to the layers on the energy spectrum of the Bernal-stacked graphene bilayer and multilayers, including graphite. We consider the minimal model with the electron tunneling…

Mesoscale and Nanoscale Physics · Physics 2010-11-15 Sergey S. Pershoguba , Victor M. Yakovenko

Electrostatically defined quantum dots (QDs) in Bernal stacked bilayer graphene (BLG) are a promising quantum information platform because of their long spin decoherence times, high sample quality, and tunability. Importantly, the shape of…

Using the continuum model, we investigate the electronic properties of two types of bilayer graphene (BLG) quantum ring (QR) geometries: (i) an isolated BLG QR and (ii) a monolayer graphene (MLG) with a QR put on top of an infinite graphene…

Mesoscale and Nanoscale Physics · Physics 2022-04-06 M. Mirzakhani , D. R. da Costa , F. M. Peeters

We present a systematic study of the energy levels of twisted bilayer graphene (tBLG) quantum dots (QD) and rings (QR) under an external perpendicular magnetic field. The confinement structures are modeled by a circular dot-like- and…

Mesoscale and Nanoscale Physics · Physics 2024-10-17 N. S. Bandeira , Andrey Chaves , L. V. de Castro , R. N. Costa Filho , M. Mirzakhani , F. M. Peeters , D. R. da Costa

We report tunneling spectroscopy experiments on a bilayer graphene double quantum dot device that can be tuned by all-graphene lateral gates. The diameter of the two quantum dots are around 50 nm and the constrictions acting as tunneling…

Mesoscale and Nanoscale Physics · Physics 2015-03-19 Christian Volk , Stefan Fringes , Bernat Terrés , Jan Dauber , Stephan Engels , Stefan Trellenkamp , Christoph Stampfer

Twisted bilayer graphene offers a unique bilayer two-dimensional-electron system where the layer separation is only in sub-nanometer scale. Unlike Bernal-stacked bilayer, the layer degree of freedom is disentangled from spin and valley,…

In bilayer graphene, electrostatic confinement can be realized by a suitable design of top and back gate electrodes. We measure electronic transport through a bilayer graphene quantum dot, which is laterally confined by gapped regions and…

Current semiconductor qubits rely either on the spin or on the charge degree of freedom to encode quantum information. By contrast, in bilayer graphene the valley degree of freedom, stemming from the crystal lattice symmetry, is a robust…

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