127,294 research outputs found
Bilayer Graphene Interferometry : Phase Jump and Wave Collimation
We theoretically study the phase of the reflection amplitude of an electron
(massive Dirac fermion) at a lateral potential step in Bernal-stacked bilayer
graphene. The phase shows anomalous jump of , as the electron incidence
angle (relative to the normal direction to the step) varies to pass . The jump is attributed to the Berry phase associated with the
pseudospin-1/2 of the electron. This Berry-phase effect is robust against the
band gap opening due to the external electric gates generating the step. We
propose an interferometry setup in which collimated waves can be generated and
tuned. By using the setup, one can identify both the jump and the
collimation angle.Comment: 4 pages, 6 figure
Large-N analysis of (2+1)-dimensional Thirring model
We analyze -dimensional vector-vector type four-Fermi interaction
(Thirring) model in the framework of the expansion. By solving the
Dyson-Schwinger equation in the large- limit, we show that in the
two-component formalism the fermions acquire parity-violating mass dynamically
in the range of the dimensionless coupling , . The symmetry
breaking pattern is, however, in a way to conserve the overall parity of the
theory such that the Chern-Simons term is not induced at any orders in .
turns out to be a non-perturbative UV-fixed point in . The
function is calculated to be
near the fixed point, and the UV-fixed point and the function are shown
exact in the expansion.Comment: 14 pages Latex. (Revised version: some changes have been made and
references added.) To appear in Phys. Rev. D, SNUTP 93-4
- …