Towards the Hall viscosity of the Fermi-liquid-like phase at the filling factor of 1/2

We discuss the Berry curvature calculations of the Hall viscosity for the unprojected to the lowest Landau level wave function of the Fermi-liquid-like state. We conclude, within assumptions made, that in the linear response, with small deformation of the system and in the thermodynamic limit, the Hall viscosity takes the value characteristic for the Laughlin states. We present arguments that the value is the same even for general deformations in the same limit.Comment: 13 pages, 6 figure

On the coexistence of antiferromagnetism and d + i d superconducting correlations in the graphene bilayer

We discuss t-J-U model on a honeycomb monolayer that has the same low-energy description of the kinetic term as graphene bilayer, and in particular study coexistence of antiferromagnetism and superconducting correlations that originate from Cooper pairs without phase coherence. We show that the model is relevant for the description of graphene bilayer and that the presence of the d + i d superconducting correlations with antiferromagnetism can lead to quadratic dependence in small magnetic fields of the gap of the effective monolayer consistent with the transport measurements of Velasco et al. on the graphene bilayer.Comment: 6 pages, 1 figure, references adde

Strain controlled valley filtering in multi-terminal graphene structures

Valley-polarized currents can be generated by local straining of multi-terminal graphene devices. The pseudo-magnetic field created by the deformation allows electrons from only one valley to transmit and a current of electrons from a single valley is generated at the opposite side of the locally strained region. We show that valley filtering is most effective with bumps of a certain height and width. Despite the fact that the highest contribution to the polarized current comes from electrons from the lowest sub-band, contributions of other sub-bands are not negligible and can significantly enhance the output current.Comment: 4 pages, 4 figure

Wavefunctional approach to the bilayer \nu =1 system and a possibility for a double non-chiral pseudospin liquid

We systematically discuss candidate wave functions for the ground state of the bilayer \nu = 1 as the distance between the layers is varied. Those that describe increased intralayer correlations at finite distance show a departure from the superflid description for smaller distances. They may support finite energy meron excitations and a dissipative collective mode in the place of the Goldstone mode of the ordered phase i.e. describe a vortex metal phase, or imply even an incompressible, pseudospin liquid, behavior. Therefore they describe possible outcomes of quantum disordering at finite distance between the layers. The vortex metal phase may show up in experiments in the presence of disorder at lower temperatures and explain the observed "imperfect superfluidity", and the pseudospin liquid phase may be the cause of the thermally activated (gapped) behavior of the longitudinal and Hall resistances at higher temperatures in counterflow experiments.Comment: 10 pages, 4 figure