21,145 research outputs found
An exact chiral spin liquid with non-Abelian anyons
We establish the existence of a chiral spin liquid (CSL) as the exact ground
state of the Kitaev model on a decorated honeycomb lattice, which is obtained
by replacing each site in the familiar honeycomb lattice with a triangle. The
CSL state spontaneously breaks time reversal symmetry but preserves other
symmetries. There are two topologically distinct CSLs separated by a quantum
critical point. Interestingly, vortex excitations in the topologically
nontrivial (Chern number ) CSL obey non-Abelian statistics.Comment: 4 pages, 2 figures; published version in Phys. Rev. Let
Fragile Mott Insulators
We prove that there exists a class of crystalline insulators, which we call
"fragile Mott insulators" which are not adiabatically connected to any sort of
band insulator provided time-reversal and certain point-group symmetries are
respected, but which are otherwise unspectacular in that they exhibit no
topological order nor any form of fractionalized quasiparticles. Different
fragile Mott insulators are characterized by different nontrivial
one-dimensional representations of the crystal point group. We illustrate this
new type of insulators with two examples: the d-Mott insulator discovered in
the checkerboard Hubbard model at half-filling and the
Affleck-Kennedy-Lieb-Tasaki insulator on the square lattice.Comment: 4 pages, 2 figures. Published version in PRL. The name "Weak Mott
Insulators" is changed to "Fragile Mott Insulators" to avoid confusing in
terminolog
Spontaneous symmetry breakings in two-dimensional kagome lattice
We study spontaneous symmetry breakings for fermions (spinless and spinful)
on a two-dimensional kagome lattice with nearest-neighbor repulsive
interactions in weak coupling limit, and focus in particular on topological
Mott insulator instability. It is found that at -filling where
there is a quadratic band crossing at -point, in agreement with Ref. 1,
the instabilities are infinitesimal and topological phases are dynamically
generated. At -filling where there are two inequivalent Dirac
points, the instabilities are finite, and no topological phase is favored at
this filling without breaking the lattice translational symmetry. A
ferromagnetic quantum anomalous Hall state with infinitesimal instability is
further proposed at half-filling of the bottom flat band.Comment: 5 pages, 3 figures, Published in Phys. Rev.
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