Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures

Abstract

Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays a crucial role in relativistic phenomena, such as Klein tunneling, but it is difficult to visualize directly. Here we report the direct observation and manipulation of chirality and pseudospin polarization in the tunneling of electrons between two almost perfectly aligned graphene crystals. We use a strong in-plane magnetic field as a tool to resolve the contributions of the chiral electronic states that have a phase difference between the two components of their vector wavefunction. Our experiments not only shed light on chirality, but also demonstrate a technique for preparing graphene's Dirac electrons in a particular quantum chiral state in a selected valley.

arXiv comment26 pages, 13 figures

References in corpus (37)

• The electronic properties of graphene
• Two-Dimensional Gas of Massless Dirac Fermions in Graphene
• Topological insulators and superconductors
• Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
• Van der Waals heterostructures
• Chiral tunneling and the Klein paradox in graphene
• Field-effect tunneling transistor based on vertical graphene heterostructures
• Dielectric function, screening, and plasmons in 2D graphene
• Asymmetry gap in the electronic band structure of bilayer graphene
• Quantum interference and Klein tunneling in graphene heterojunctions
• The electronic properties of bilayer graphene
• Spintronics and Pseudospintronics in Graphene and Topological Insulators
• Weak localisation magnetoresistance and valley symmetry in graphene
• Kohn Anomalies and Electron-Phonon Interaction in Graphite
• Zitterbewegung, chirality, and minimal conductivity in graphene
• Landau level spectroscopy of ultrathin graphite layers
• Tunable metal-insulator transition in double-layer graphene heterostructures
• First direct observation of Dirac fermions in graphite
• Twist-controlled resonant tunnelling in graphene-boron nitride-graphene heterostructures
• Electronic Properties of Graphene Encapsulated with Different Two-Dimensional Atomic Crystals
• Weak localisation in graphene flakes
• Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles
• Electron-electron interactions and doping dependence of the two-phonon Raman intensity in graphene
• Impact of the electron-electron correlation on phonon dispersions: failure of LDA and GGA functionals in graphene and graphite
• Gate-Tunable Resonant Tunneling in Double Bilayer Graphene Heterostructures
• Two-dimensional surface charge transport in topological insulators
• Single-Particle Tunneling in Doped Graphene-Insulator-Graphene Junctions
• Characterization of graphene through anisotropy of constant-energy maps in angle-resolved photoemission
• Inelastic carrier lifetime in graphene
• Phonon-assisted resonant tunneling of electrons in graphene-boron nitride transistors
• Tunneling Spectroscopy of Graphene-Boron Nitride Heterostructures
• Theory of Graphene-Insulator-Graphene Tunnel Junctions
• Coherent tunneling and negative differential conductivity in graphene-hBN-graphene heterostructure
• Resonant and non-dissipative tunneling in independently contacted graphene structures
• Twist-controlled Resonant Tunnelling between Monolayer and Bilayer Graphene
• Resonant tunneling and the quasiparticle lifetime in graphene/boron nitride/graphene heterostructures
• Magneto-tunnelling spectroscopy of chiral two-dimensional electron systems

Cited by in corpus (35)

• Twistable electronics with dynamically rotatable heterostructures
• Magnon-assisted tunnelling in van der Waals heterostructures based on CrBr3
• Spectroscopic studies of atomic defects and bandgap renormalization in semiconducting monolayer transition metal dichalcogenides
• 2D MoS2-Graphene-based multilayer van der Waals heterostructures: Enhanced charge transfer and optical absorption, and electric-field tunable Dirac point and band gap
• The Quantum Twisting Microscope
• Composite super-moiré lattices in double aligned graphene heterostructures
• High intrinsic lattice thermal conductivity in monolayer MoSi${}_2$N${}_4$
• Electron quantum metamaterials in van der Waals heterostructures
• Valley Polarization and Inversion in Strained Graphene via Pseudo-Landau Levels, Valley Splitting of Real Landau Levels and Confined States
• Large tunable valley splitting in edge-free graphene quantum dots on boron nitride
• Coherent Interlayer Tunneling and Negative Differential Resistance with High Current Density in Double Bilayer Graphene-WSe2 Heterostructures
• Signatures of phonon and defect-assisted tunneling in planar metal-hexagonal boron nitride-graphene junctions
• One-step synthesis of van der Waals heterostructures of graphene and 2D superconducting a-Mo2C
• Planar and van der Waals heterostructures for vertical tunnelling single electron transistors
• Sub-bandgap voltage electroluminescence and magneto-oscillations in a WSe2 light-emitting van der Waals heterostructure
• Valley filtering and electronic optics using polycrystalline graphene
• Tunnel spectroscopy of localised electronic states in hexagonal boron nitride
• Parity-Dependent Moiré Superlattices in Graphene/h-BN Heterostructures: A Route to Mechanomutable Metamaterials
• Symmetry breaking and (pseudo)spin polarization in Veselago lenses for massless Dirac fermions
• Observation of Chirality Transition of Quasiparticles at Stacking Solitons in Trilayer Graphene
• Chiral photonic super-crystals based on helical van der Waals homostructures
• Gate-versus defect-induced voltage drop and negative differential resistance in vertical graphene heterostructures
• Minimal Geometry for Valley Filtering in Graphene
• Tunneling spectroscopy of localized states of ${\mathrm{WS}}_2$ barriers in vertical van der Waals heterostructures
• Twisted monolayer and bilayer graphene for vertical tunneling transistors
• Observation of time-reversal symmetric Hall effect in graphene-WSe2 heterostructures at room temperature
• Plasmon-assisted resonant tunneling in graphene-based heterostructures
• Valley-polarised tunnelling currents in bilayer graphene tunnelling transistors
• Gigantic tunneling magnetoresistance in magnetic Weyl semimetal tunnel junctions
• Quantum Lifetime Spectroscopy and Magnetotunneling in Double Bilayer Graphene Heterostructures
• A magnetically-induced Coulomb gap in graphene due to electron-electron interactions
• Negative differential resistance in Van der Waals heterostructures due to moiré-induced spectral reconstruction
• Topological Insulator Metamaterial with Giant Circular Photogalvanic Effect
• Probing the features of electron dispersion by tunneling between slightly twisted bilayer graphene sheets
• Insulator-Metal Transition and Magnetic Crossover in Bilayer Graphene