7,244 research outputs found
Analytical theory of dark nonlocal solitons
We investigate properties of dark solitons in nonlocal materials with an
arbitrary degree of nonlocality. We employ the variational technique and
describe the dark solitons, for the first time, in the whole range of degree of
nonlocality.Comment: to be published in Optics Letter
Buddhism Co. Ltd? Epistemology of religiosity, and the re-invention of a Buddhist monastery in Hong Kong
Two-Dimensional Topological Insulator State and Topological Phase Transition in Bilayer Graphene
We show that gated bilayer graphene hosts a strong topological insulator (TI)
phase in the presence of Rashba spin-orbit (SO) coupling. We find that gated
bilayer graphene under preserved time-reversal symmetry is a quantum valley
Hall insulator for small Rashba SO coupling , and
transitions to a strong TI when ,
where and are respectively the interlayer potential and tunneling
energy. Different from a conventional quantum spin Hall state, the edge modes
of our strong TI phase exhibit both spin and valley filtering, and thus share
the properties of both quantum spin Hall and quantum valley Hall insulators.
The strong TI phase remains robust in the presence of weak graphene intrinsic
SO coupling.Comment: 5 pages and 4 figure
Topological phases in gated bilayer graphene: Effects of Rashba spin-orbit coupling and exchange field
We present a systematic study on the influence of Rashba spin-orbit coupling,
interlayer potential difference and exchange field on the topological
properties of bilayer graphene. In the presence of only Rashba spin-orbit
coupling and interlayer potential difference, the band gap opening due to
broken out-of-plane inversion symmetry offers new possibilities of realizing
tunable topological phase transitions by varying an external gate voltage. We
find a two-dimensional topological insulator phase and a quantum valley
Hall phase in -stacked bilayer graphene and obtain their effective
low-energy Hamiltonians near the Dirac points. For stacking, we do not
find any topological insulator phase in the presence of large Rashba spin-orbit
coupling. When the exchange field is also turned on, the bilayer system
exhibits a rich variety of topological phases including a quantum anomalous
Hall phase, and we obtain the phase diagram as a function of the Rashba
spin-orbit coupling, interlayer potential difference, and exchange field.Comment: 15 pages, 17figures, and 1 tabl
Analytical theory for dark soliton interaction in nonlocal nonlinear materials with arbitrary degree of nonlocality
We investigate theoretically the interaction of dark solitons in materials
with a spatially nonlocal nonlinearity. In particular we do this analytically
and for arbitrary degree of nonlocality. We employ the variational technique to
show that nonlocality induces an attractive force in the otherwise repulsive
soliton interaction.Comment: submitted for publicatio
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