Broken symmetry states and Quantum Hall Ferromagnetism in decoupled twisted bilayer graphene

• URL: http://arxiv.org/abs/2503.20392v1
• Date: Wed, 26 Mar 2025 10:15:22 GMT
• Title: Broken symmetry states and Quantum Hall Ferromagnetism in decoupled twisted bilayer graphene
• Authors: Vineet Pandey, Prasenjit Ghosh, Riju Pal, Sourav Paul, Abhijith M B, Kenji Watanabe, Takashi Taniguchi, Atindra Nath Pal, Vidya Kochat,
• Abstract summary: Twisted bilayer graphene (TBLG) with large twist angle is a novel 2D bilayer system with strong interlayer Coulomb interactions.<n>We demonstrate the role of charge screening effects in electronically decoupled TBLG.
• Score: 0.41819706568983034
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Twisted bilayer graphene (TBLG) with large twist angle is a novel 2D bilayer system with strong interlayer Coulomb interactions, whilst suppressed interlayer carrier tunneling due to momentum mismatch between the Dirac cones of individual graphene layers. This interlayer decoherence disentangles the layer degree of freedom from spin-valley space. We demonstrate the role of charge screening effects in electronically decoupled TBLG that determines the Landau level (LL) crossings and multicomponent Quantum Hall (QH) effect resulting from combinations of broken symmetry states with spin and valley flavors of constituent layers.The N = 0 LL at zero filling factor is characterized by a field-induced Kosterlitz-Thouless transition to an ordered ground state, consistent with predictions of intervalley coherent state of Kekul\'e order. Pronounced hysteresis and electron-hole asymmetry observed in the QH regime suggests pinning of low-energy topological excitations, i.e., skyrmions with spin and valley textures, at charged defects in graphene channel.

Related papers

• Dissipative phase transitions of the Dicke-Ising model [2.4851820343103035]
  We study the dissipative phase transitions in the open transverse and longitudinal Dicke-Ising model (DIM)<n>Our results reveal that the interplay among spin interactions, light-matter coupling, and dissipation supports a diverse set of nonequilibrium phase transitions.<n>These findings offer a theoretical foundation for exploring nonequilibrium physics in realistic open solid-state quantum systems.
  arXiv  Detail & Related papers  (2026-02-10T15:44:02Z)
• Quantum Hall Effect at 0.002T [46.680073344221626]
  We demonstrate a significant reduction in external inhomogeneity using a double-layer graphene architecture separated by an ultra-thin hexagonal boron nitride layer.<n>Shubnikov de-Haas oscillations emerge at magnetic fields below 1 mT, while integer quantum Hall features are observed at 0.002T.<n>These results demonstrate the platform's suitability for investigating strongly correlated electronic phases in graphene-based heterostructures.
  arXiv  Detail & Related papers  (2026-01-22T14:40:33Z)
• Topological crystals and soliton lattices in a Gross-Neveu model with Hilbert-space fragmentation [41.94295877935867]
  We explore the finite-density phase diagram of the single-flavour Gross-Neveu-Wilson (GNW) model.<n>We find a sequence of inhomogeneous ground states that arise through a real-space version of the mechanism of Hilbert-space fragmentation.
  arXiv  Detail & Related papers  (2025-06-23T14:19:35Z)
• Topological Signatures of Magnetic Phase Transitions with Majorana Fermions through Local Observables and Quantum Information [2.7204116565403744]
  The one-dimensional (1D) $J_1-J$ quantum spin model can be viewed as a strong-coupling analogue of the Schrieffer-Su-Heeger model.<n>This model also maps onto a p-wave superconducting wire which shows a topological phase transition with the emergence of low-energy Majorana fermions.<n>This system may be realized in materials and engineered in quantum circuits, optical lattices.
  arXiv  Detail & Related papers  (2025-06-13T12:43:34Z)
• Interaction-Driven Intervalley Coherence with Emergent Kekulé Orbitons [2.4308418561106215]
  The Dirac fermions with linear dispersion at $pm K$ valleys govern the non-interacting low-energy physics.<n>Surprisingly, the intermediate many-particle interaction produces the intervalley coherence between $pm K$ valleys.<n>Our findings provide insights for a direction of searching for Kekul'e distortion in correlated multi-orbital systems.
  arXiv  Detail & Related papers  (2025-05-05T08:45:08Z)
• Emergent Kitaev materials in synthetic Fermi-Hubbard bilayers [49.1574468325115]
  Bond-directional spin-spin interactions in a Fermi-Hubbard bilayer can be realized with ultracold fermions in Raman optical lattices. We analyze the Fermi-liquid and Mott-insulating phases, highlighting a correspondence between Dirac and Majorana quasi-particles. Our results establish that cold-atom quantum simulators based on Raman optical lattices can be a playground for extended Kitaev models.
  arXiv  Detail & Related papers  (2025-04-22T10:07:56Z)
• Tunable Topological Phases in Multilayer Graphene Coupled to a Chiral Cavity [0.0]
  Coupling photonic cavity fields to electronic degrees of freedom in 2D materials introduces an additional control knob to the toolbox of solid-state engineering. We demonstrate a subtle competition between cavity frequency and interlayer tunneling in graphene stacks that is responsible for topological phase transitions in light-matter Hilbert space. Our findings pave the way for future control and engineering of graphene heterostructures with chiral cavity fields.
  arXiv  Detail & Related papers  (2025-04-04T18:00:05Z)
• Constrained many-body phases in a $\mathbb{Z}_2$-Higgs lattice gauge theory [39.58317527488534]
  We study a one-dimensional $mathbbZ$ lattice gauge theory coupled to soft-core bosonic matter at unit filling.<n>Through a combination of analytical perturbative approaches, we uncover a rich phase diagram driven by gauge-field-mediated resonant pair hopping.<n>The presence of a bunching state with large number fluctuations motivates experimental realizations in hybrid boson-qubit quantum simulation platforms.
  arXiv  Detail & Related papers  (2025-03-05T19:00:07Z)
• Harnessing Chiral Spin States in Molecular Nanomagnets for Quantum Technologies [44.1973928137492]
  We show that chiral qubits naturally suppress always-on interactions that can not be switched off in weakly coupled qubits. Our findings establish spin chirality engineering as a promising strategy for mitigating always-on interaction in entangling two chiral qubits in molecular quantum technologies.
  arXiv  Detail & Related papers  (2025-01-21T08:23:12Z)
• Quantum Phase Diagram of the Bilayer Kitaev-Heisenberg Model [0.0]
  We study the ground-state phase diagram of the Kitaev-Heisenberg model on the bilayer honeycomb lattice.<n>We find that beyond various magnetically ordered phases, two extended quantum spin liquid phases arise in the proximity of the Kitaev limit.
  arXiv  Detail & Related papers  (2024-12-23T11:53:01Z)
• Imaging Coulomb interactions and migrating Dirac cones in twisted graphene by local quantum oscillations [0.23191656838250044]
  We use a nanoscale scanning superconducting quantum interference device to image the local thermodynamic quantum oscillations in alternating-twist trilayer graphene at magnetic fields as low as 56 mT. We find that the charging self-energy due to occupied electronic states, is critical in explaining the high carrier density physics. At half-filling of the conduction flat band, we observe a Stoner-like symmetry breaking, suggesting that it is the most robust mechanism in the hierarchy of phase transitions.
  arXiv  Detail & Related papers  (2024-07-15T12:47:22Z)
• Shaping the topology of twisted bilayer graphene via time-reversal symmetry breaking [0.0]
  We utilize time-reversal symmetry breaking to manipulate the topological properties of twisted bilayer graphene (TBG) By varying the strength of TRSB, we discover a topological phase transition between a topological insulating phase, which exhibits a pair of flat bands with opposite Chern numbers. We show that this novel electronic phase can be identified in the lab by measuring, as a function of the Fermi energy, its non-quantized anomalous Hall conductivity.
  arXiv  Detail & Related papers  (2024-06-05T05:14:28Z)
• Ferrimagnetism of ultracold fermions in a multi-band Hubbard system [34.95884242542007]
  We report on signatures of a ferrimagnetic state realized in a Lieb lattice at half-filling. We demonstrate its robustness when increasing repulsive interactions from the non-interacting to the Heisenberg regime. Our work paves the way towards exploring exotic phases in related multi-orbital models such as quantum spin liquids in kagome lattices and heavy fermion behavior in Kondo models.
  arXiv  Detail & Related papers  (2024-04-26T17:33:26Z)
• Dynamical correlations and order in magic-angle twisted bilayer graphene [0.272760415353533]
  We study the emergence of electronic correlations and long-range order in twisted bilayer graphene. Our findings provide a unified understanding of the most puzzling aspects of scanning tunneling spectroscopy, transport, and compressibility experiments.
  arXiv  Detail & Related papers  (2023-09-15T16:46:36Z)
• Understanding Symmetry Breaking in Twisted Bilayer Graphene from Cluster Constraints [0.11249583407496218]
  We investigate the phase diagram of twisted bilayer graphene as described by an extended Hubbard model on the honeycomb lattice with two fermionic orbitals (valleys) per site. Within Quantum Monte Carlo (QMC), we find valence-bond-solid, N'eel-valley antiferromagnetic or charge-density wave phases. Our work capitalizes on the notion of cluster constraints in the extended Hubbard model of twisted bilayer graphene, and suggests a scheme towards realization of several symmetry-breaking insulating phases in a twisted-bilayer graphene sheet.
  arXiv  Detail & Related papers  (2023-08-16T18:00:01Z)
• Photoinduced prethermal order parameter dynamics in the two-dimensional large-$N$ Hubbard-Heisenberg model [77.34726150561087]
  We study the microscopic dynamics of competing ordered phases in a two-dimensional correlated electron model. We simulate the light-induced transition between two competing phases.
  arXiv  Detail & Related papers  (2022-05-13T13:13:31Z)
• Tuning long-range fermion-mediated interactions in cold-atom quantum simulators [68.8204255655161]
  Engineering long-range interactions in cold-atom quantum simulators can lead to exotic quantum many-body behavior. Here, we propose several tuning knobs, accessible in current experimental platforms, that allow to further control the range and shape of the mediated interactions.
  arXiv  Detail & Related papers  (2022-03-31T13:32:12Z)
• Variational Quantum Simulation of Valence-Bond Solids [0.0]
  We introduce a hybrid quantum-classical variational algorithm to simulate ground-state phase diagrams of frustrated quantum spin models. We benchmark the method against the J1-J2 Heisenberg model on the square lattice and uncover its phase diagram. Our results show that the convergence of the algorithm is guided by the onset of long-range order, opening a promising route to synthetically realize frustrated quantum magnets.
  arXiv  Detail & Related papers  (2022-01-07T17:05:14Z)
• Phase diagram of Rydberg-dressed atoms on two-leg square ladders: Coupling supersymmetric conformal field theories on the lattice [52.77024349608834]
  We investigate the phase diagram of hard-core bosons in two-leg ladders in the presence of soft-shoulder potentials. We show how the competition between local and non-local terms gives rise to a phase diagram with liquid phases with dominant cluster, spin, and density-wave quasi-long-range ordering.
  arXiv  Detail & Related papers  (2021-12-20T09:46:08Z)
• Quantum correlations, entanglement spectrum and coherence of two-particle reduced density matrix in the Extended Hubbard Model [62.997667081978825]
  We study the ground state properties of the one-dimensional extended Hubbard model at half-filling. In particular, in the superconducting region, we obtain that the entanglement spectrum signals a transition between a dominant singlet (SS) to triplet (TS) pairing ordering in the system.
  arXiv  Detail & Related papers  (2021-10-29T21:02:24Z)
• Phase diagram of a distorted kagome antiferromagnet and application to Y-kapellasite [50.591267188664666]
  We reveal a rich ground state phase diagram even at the classical level. The presented model opens a new direction in the study of kagome antiferromagnets.
  arXiv  Detail & Related papers  (2021-07-28T18:00:03Z)
• Nonequilibrium phase transition in a driven-dissipative quantum antiferromagnet [0.0]
  This paper provides a numerical study of dynamical phases and the transitions between them in the nonequilibrium steady state of the prototypical two-dimensional Heisenberg antiferromagnet with drive and dissipation. A finite-size analysis reveals static and dynamical critical scaling at the transition, with a discontinuous slope of the magnon number versus driving field strength and critical slowing down at the transition point.
  arXiv  Detail & Related papers  (2021-07-08T13:35:00Z)
• Chemical tuning of spin clock transitions in molecular monomers based on nuclear spin-free Ni(II) [52.259804540075514]
  We report the existence of a sizeable quantum tunnelling splitting between the two lowest electronic spin levels of mononuclear Ni complexes. The level anti-crossing, or magnetic clock transition, associated with this gap has been directly monitored by heat capacity experiments. The comparison of these results with those obtained for a Co derivative, for which tunnelling is forbidden by symmetry, shows that the clock transition leads to an effective suppression of intermolecular spin-spin interactions.
  arXiv  Detail & Related papers  (2021-03-04T13:31:40Z)
• Entanglement robustness to excitonic spin precession in a quantum dot [43.55994393060723]
  A semiconductor quantum dot (QD) is an attractive resource to generate polarization-entangled photon pairs. We study the excitonic spin precession (flip-flop) in a family of QDs with different excitonic fine-structure splitting (FSS) Our results reveal that coherent processes leave the time post-selected entanglement of QDs unaffected while changing the eigenstates of the system.
  arXiv  Detail & Related papers  (2020-01-31T13:50:51Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.