Complete Spin and Valley Polarization by Total External Reflection from Potential Barriers in Bilayer Graphene and Monolayer Transition Metal Dichalcogenides
arXiv:1911.03077 · doi:10.1103/PhysRevB.104.155401
Abstract
It is shown that potential barriers in bilayer graphene (BLG) and monolayer transition metal dichalcogenides (TMDs) can split a valley unpolarized incident current into reflected and transmitted currents with opposite valley polarization. Valley asymmetric transmission inevitably occurs because of the low symmetry of the total Hamiltonian and when total external reflection occurs the transmission is 100% valley polarized in BLG and 100% spin and valley polarized in TMDs, except for exponentially small corrections. By adjusting the potential, 100% polarization can be obtained regardless of the crystallographic orientation of the barrier. A valley polarizer can be realized by arranging for a collimated beam of carriers to be incident on a barrier within the range of angles for total external reflection. The transmission coefficients of barriers with a relative rotation of are related by symmetry. This allows two barriers to be used to demonstrate that the current is valley polarized. A soft-walled potential is used to model the barrier and the method used to find the transmission coefficients is explained. In the case of monolayer TMDs, a 4-band k.p Hamiltonian is used and the k.p parameters are obtained by fitting to ab-initio band structures.
21 pages, 16 figures; merged paper and supplemental material; updated references
References in corpus (41)
- Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
- Valley contrasting physics in graphene: magnetic moment and topological transport
- The Valley Hall Effect in MoS2 Transistors
- High Performance Single Layered WSe2 p-FETs with Chemically Doped Contacts
- Mobility engineering and metal-insulator transition in monolayer MoS2
- Valley filter and valley valve in graphene
- Substrate-induced bandgap in graphene on hexagonal boron nitride
- Asymmetry gap in the electronic band structure of bilayer graphene
- Graphene field-effect-transistors with high on/off current ratio and large transport band gap at room temperature
- The electronic properties of bilayer graphene
- k.p theory for two-dimensional transition metal dichalcogenide semiconductors
- Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides
- Graphene valley filter using a line defect
- Generation and detection of pure valley current by electrically induced Berry curvature in bilayer graphene
- Monolayer MoS2: trigonal warping, "Γ-valley", and spin-orbit coupling effects
- Valley Chern Numbers and Boundary Modes in Gapped Bilayer Graphene
- Gate-tunable Topological Valley Transport in Bilayer Graphene
- Strain-induced pseudo-magnetic field for novel graphene electronics
- Valley-dependent Brewster angles and Goos-Hanchen effect in strained graphene
- Field-induced polarisation of Dirac valleys in bismuth
- Tunable band gaps in bilayer graphene-BN heterostructures
- Effective lattice Hamiltonian for monolayer MoS2 : Tailoring electronic structure with perpendicular electric and magnetic fields
- Valley splitting of AlAs two-dimensional electrons in a perpendicular magnetic field
- Valley Polarization in Si(100) at Zero Magnetic Field
- Generation of valley polarized current in bilayer graphene
- Influence of disorder on conductance in bilayer graphene under perpendicular electric field
- Valley Polarization and Inversion in Strained Graphene via Pseudo-Landau Levels, Valley Splitting of Real Landau Levels and Confined States
- Fabry-Pérot interference in gapped bilayer graphene with broken anti-Klein tunneling
- Charge transport in dual gated bilayer graphene with Corbino geometry
- Electron-hole collision limited transport in charge-neutral bilayer graphene
- Electronic transmission through AB-BA domain boundary in bilayer graphene
- Quantized conductance in an AlAs 2D electron system quantum point contact
- Helical scattering and valleytronics in bilayer graphene
- Absorptive pinhole collimators for ballistic Dirac fermions in graphene
- Coherent Jetting behind a gate-defined Channel in Bilayer Graphene
- Dirac fermion quantization on graphene edges: Isospin-orbit coupling, zero modes and spontaneous valley polarization
- Trigonal Warping in Bilayer Graphene: Energy versus Entanglement Spectrum
- Intraband electron focusing in bilayer graphene
- Spin-dependent Refraction at the Atomic Step of Transition-metal Dichalcogenides
- Electrical valley filtering in transition metal dichalcogenides
- Theory of valley-dependent transport in graphene-based lateral quantum structures