1,095 research outputs found
Domain walls in gapped graphene
The electronic properties of a particular class of domain walls in gapped
graphene are investigated. We show that they can support mid-gap states which
are localized in the vicinity of the domain wall and propagate along its
length. With a finite density of domain walls, these states can alter the
electronic properties of gapped graphene significantly. If the mid-gap band is
partially filled,the domain wall can behave like a one-dimensional metal
embedded in a semi-conductor, and could potentially be used as a single-channel
quantum wire.Comment: 4 pgs. revte
Strong Coupling Qed Breaks Chiral Symmetry
We show that the strong coupling limit of d-dimensional quantum
electrodynamics with flavors of fermions can be mapped onto
the s=1/2 quantum Heisenberg antiferromagnet in d-1 space dimensions. The
staggered N\'eel order parameter is the expectation value of a mass operator in
QED and the spin-waves are pions. We speculate that the chiral symmetry
breaking phase transition corresponds to a transition between the flux phase
and the conventional N\'eel ordered phase of an antiferromagnetic t-J model.Comment: 11page
Electronic zero modes of vortices in Hall states of gapped graphene
Recent observation of a metal-insulator phase transition in the Hall
state of graphene has inspired the idea that charge carriers in the metallic
state could be fractionally charged vortices. We examine the question of
whether vortices in particular gapped states of graphene and subject to
external magnetic and pseudo-magnetic fields could have the mid-gap zero mode
electron states which would allow them to be charged.Comment: 8pg
D3-D5 Holography with Flux
It is shown that the Berezinski-Kosterlitz-Thouless phase transition that has
been found in D3-D5 brane systems with nonzero magnetic field and charge
density can also be found by tuning an extra-dimensional magnetic flux. We find
numerical solutions for the probe D5-brane embedding and discuss properties of
the solutions. We also demonstrate that the nontrivial embeddings include those
which can be regarded as spontaneously breaking chiral symmetry
Spin Versus Charge Density Wave Order in Graphene-like Systems
A variational technique is used to study sublattice symmetry breaking by
strong on-site and nearest neighbor interactions in graphene. When interactions
are strong enough to break sublattice symmetry, and with relative strengths
characteristic of graphene, a charge density wave Mott insulator is favored
over the spin density wave condensates. In the spin density wave condensate we
find that introduction of a staggered on-site energy (quasiparticle mass) leads
to a splitting of the fermi velocities and mass gaps of the quasiparticle spin
states.Comment: 5 pages, 4 figures; some comments adde
Quantum insulating states of F=2 cold atoms in optical lattices
In this Letter we study various spin correlated insulating states of F=2 cold
atoms in optical lattices. We find that the effective spin exchange interaction
due to virtual hopping contains an {\em octopole} coupling between two
neighboring lattice sites. Depending on scattering lengths and numbers of
particles per site the ground states are either rotationally invariant dimer or
trimer Mott insulators or insulating states with various spin orders. Three
spin ordered insulating phases are ferromagnetic, cyclic and nematic Mott
insulators. We estimate the phase boundaries for states with different numbers
of atoms per lattice site.Comment: 4 pages, 1 figure include
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