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.

26 pages, 13 figures

References in corpus (16)

• The electronic properties of graphene
• Chiral tunneling and the Klein paradox in graphene
• 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
• Weak localisation magnetoresistance and valley symmetry in graphene
• Landau level spectroscopy of ultrathin graphite layers
• First direct observation of Dirac fermions in graphite
• Twist-controlled resonant tunnelling in graphene-boron nitride-graphene heterostructures
• Weak localisation in graphene flakes
• 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
• Characterization of graphene through anisotropy of constant-energy maps in angle-resolved photoemission
• Inelastic carrier lifetime in graphene
• Coherent tunneling and negative differential conductivity in graphene-hBN-graphene heterostructure

Cited by in corpus (22)

• Spectroscopic studies of atomic defects and bandgap renormalization in semiconducting monolayer transition metal dichalcogenides
• The Quantum Twisting Microscope
• Composite super-moiré lattices in double aligned graphene heterostructures
• High intrinsic lattice thermal conductivity in monolayer MoSi${}_2$N${}_4$
• 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
• Sub-bandgap voltage electroluminescence and magneto-oscillations in a WSe2 light-emitting van der Waals heterostructure
• Planar and van der Waals heterostructures for vertical tunnelling single electron transistors
• 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
• Twisted monolayer and bilayer graphene for vertical tunneling transistors
• Minimal Geometry for Valley Filtering in Graphene
• Observation of time-reversal symmetric Hall effect in graphene-WSe2 heterostructures at room temperature
• Plasmon-assisted resonant tunneling in graphene-based heterostructures
• 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
• Topological Insulator Metamaterial with Giant Circular Photogalvanic Effect
• Insulator-Metal Transition and Magnetic Crossover in Bilayer Graphene
• Probing the features of electron dispersion by tunneling between slightly twisted bilayer graphene sheets