607 research outputs found
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
- …