Related papers: Valley separation via trigonal warping
We show that the valley Chern number of the low energy band in twisted double bilayer graphene can be tuned through two successive topological transitions, where the direct bandgap closes, by changing the electric field perpendicular to the…
Valley-dependent topological physics offers a promising avenue for designing nanoscale devices based on gapless single-layer graphene. To demonstrate this potential, we investigate an electrical bias-controlled topological discontinuity in…
Coherent manipulation of binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid state…
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,…
The differences in energy between electronic bands due to valley splitting are of paramount importance in interpreting transport spectroscopy experiments on state-of-the-art quantum devices defined by scanning tunneling microscope…
Electrons in certain two-dimensional crystals possess a pseudospin degree of freedom associated with the existence of two inequivalent valleys in the Brillouin zone. If, as in monolayer MoS2, inversion symmetry is broken and time-reversal…
Abstract The valley degree of freedom in two-dimensional materials provides an opportunity to extend the functionalities of valleytronics devices. Very short valley lifetimes demand the ultrafast control of valley pseudospin. Here, we…
An established way of realizing topologically protected states in a two-dimensional electron gas is by applying a perpendicular magnetic field thus creating quantum Hall edge channels. In electrostatically gapped bilayer graphene…
Modulation of electronic states in two-dimensional (2D) materials can be achieved by using in-plane variations of the band gap or the average potential in lateral quantum structures. In the atomic configurations with hexagonal symmetry,…
We study spin and valley-dependent transport properties in an n-p-n junction of 8-pmmn borophene monolayer. An external gate voltage and exchange magnetic field, induced by the proximity effect of a ferromagnetic insulator, are applied to…
Particular strain geometry in graphene could leads to a uniform pseudo-magnetic field of order 10T and might open up interesting applications in graphene nano-electronics. Through quantum transport calculations of realistic strained…
Magic-angle twisted bilayer graphene displays a complex phase diagram as a function of flat band filling, featuring compressibility cascade transitions and a variety of competing ground states with broken spin, valley and point group…
Valley pseudospin, the quantum degree of freedom characterizing the degenerate valleys in energy bands, is a distinct feature of two-dimensional Dirac materials. Similar to spin, the valley pseudospin is spanned by a time reversal pair of…
We study the states localized near an interface between conducting and insulating bilayer graphene (BLG) and show that they have highly unusual properties that have no analog in conventional systems. Moreover, the states belonging to the…
In addition to electron charge and spin, novel materials host another degree of freedom, the valley. For a junction composed of valley filter sandwiched by two normal terminals, we focus on the valley efficiency under disorder with two…
We report on a theoretical study of one-dimensional (1D) states localized at few-layer graphene system ribbon edges, and at interfaces between few-layer graphene systems with different valley Hall conductivities. These 1D states are…
Superlattices (SLs) in monolayer and bilayer graphene, formed by spatially periodic potential variations, lead to a modified bandstructure with extra finite-energy and zero-energy Dirac fermions with tunable anisotropic velocities. We…
We study the effect of the strain on the band structure and the valley-dependent transport property of graphene heterojunctions. It is found that valley-dependent separation of electrons can be achieved by utilizing the strain and on-site…
The valley degree of freedom in 2D materials can be manipulated for low-dissipation quantum electronics called valleytronics. At the boundary between two regions of bilayer graphene with different atomic or electrostatic configuration,…
We propose a valley- and spin-filter based on a normal/ferromagnetic/normal molybdenum disulfide (MoS$_2$) junction where the polarizations of the valley and the spin can be inverted by reversing the direction of the exchange field in the…