arXiv subjects

Vadim Cheianov

Publications and source records attributed to Vadim Cheianov.

27 records · Page 2Linked to original sources

arXiv2015

Scaling dimension of quantum Hall quasiparticles from tunneling current noise measurements

Determination of properties of quasiparticle excitations is an important task in the experimental investigation of the fractional quantum Hall effect (FQHE). We propose a model-independent method for finding the scaling dimension of FQHE quasiparticles from measurements of the electric current tunneling between two FQHE edges and its noise. In comparison to the commonly used method based on measuring the tunneling current only, the proposed method is less prone to the errors due to non-universal physics of tunnel junctions.

cond-mat.str-el↗

arXiv2014

Moire pattern as a magnifying glass for strain and dislocations in van der Waals heterostructures

We consider the role of deformations in graphene heterostructures with hexagonal crystals (including strain, wrinkles and dislocations) on the geometrical properties of moire patterns characteristic for a pair of two incommensurate misaligned isostructural crystals. By, employing a phenomenological theory to describe generic moire perturbation in van der Waals heterostructures of graphene and hexagonal crystals we investigate the electronic properties of such heterostructure.

cond-mat.mes-hall↗

arXiv2013

Mesoscopic fluctuations of conductance of a helical edge contaminated by magnetic impurities

Elastic backscattering of electrons moving along the helical edge is prohibited by time-reversal symmetry (TRS). We demonstrate, however, that an ensemble of magnetic impurities may cause TRS-preserving quasi-elastic backscattering, resulting in interference effects in the conductance. The characteristic energy transferred in a backscattering event is suppressed due to the RKKY interaction of localized spins (the suppression is exponential in the total number of magnetic impurities). We predict the statistics of conductance fluctuations to differ from those in the conventional case of a one-dimensional system with quenched disorder.

cond-mat.mes-hall↗

arXiv2012

Phases of the excitonic condensate in two-layer graphene

Two graphene monolayers that are oppositely charged and placed close to each other are considered. Taking into account valley and spin degeneracy of electrons we analyze the symmetry of the excitonic insulator states in such a system and build a phase diagram that takes into account the effect of the symmetry breaking due to the external in-plane magnetic field and the carrier density imbalance between the layers.

cond-mat.mes-hall↗

arXiv2012

Classical and quantum magneto-oscillations of current flow near a p-n junction in graphene

The proposed semiclassical theory predicts two types of oscillations in the flow of current injected from a point source near a ballistic p-n junction in graphene in a strong magnetic field. One originates from the classical effect of bunching of cyclotron orbits of electrons passing back and forth across the p-n interface, which displays a pronounced dependence on the commensurability between the cyclotron radii in the n- and p-regions. The other effect is caused by the interference of monochromatic electron waves in p-n junctions with equal carrier densities on the two sides and it consists in magneto-oscillations in the current transmission through the interface with periodicity similar to Shubnikov-de Haas oscillations.

cond-mat.mes-hall↗

arXiv2012

Importance of interband transitions for the fractional quantum Hall effect in bilayer graphene

Several recent works have proposed that electron-electron interactions in bilayer graphene can be tuned with the help of external parameters, making it possible to stabilize different fractional quantum Hall states. In these prior works, phase diagrams were calculated based on a single Landau level approximation. We go beyond this approximation and investigate the influence of polarization effects and virtual interband transitions on the stability of fractional quantum Hall states in bilayer graphene. We find that for realistic values of the dielectric constant, the phase diagram is strongly modified by these effects. We illustrate this by evaluating the region of stability of the Pfaffian state.

cond-mat.str-el↗

arXiv2011

Skipping and snake orbits of electrons: singularities and catastrophes

Near the sample edge, or a sharp magnetic field step the drift of two-dimensional electrons in a magnetic field has the form of skipping/snake orbits. We show that families of skipping/snake orbits of electrons injected at one point inside a 2D metal generically exhibit caustics folds, cusps and cusp triplets, and, in one extreme case, a section of the batterfly bifurcation. Periodic appearance of singularities along the $\pm B$-interface leads to the magneto-oscillations of nonlocal conductance in multi-terminal electronic devices.

cond-mat.mes-hall↗

arXiv2011

Transport anomaly at the ordering transition for adatoms on graphene

We analyze a manifestation of the partial ordering transition of adatoms on graphene in resistivity measurements. We find that Kekule mosaic ordering of adatoms increases sheet resistance of graphene, due to a gap opening in its spectrum, and that critical fluctuations of the order parameter lead to a non-monotonic temperature dependence of resistivity, with a cusp-like minimum at T=T_c.

cond-mat.dis-nn↗

arXiv2009

Effective field theories for the $ν= 5/2$ edge

We present a list of possible effective theories which may describe a QHE edge at filling fraction $ν=5/2$. We show that there exist several abelian and non-abelian effective theories (apart from those discussed in the literature) compatible with the physical requirements imposed by the microscopic nature of the system. We compare predictions of these theories with previous proposals and with the results of recent experiments. We identify a set of theories, both abelian and non-abelian, that cannot be distinguished based on the quasihole tunneling data only. We discuss what experimental information may be useful in resolving the ambiguity.

cond-mat.str-el↗