777 research outputs found
Edge modes in the Hofstadter model of interacting electrons
We provide a detailed analysis of a realization of chiral gapless edge modes
in the framework of the Hofstadter model of interacting electrons. In a
transverse homogeneous magnetic field and a rational magnetic flux through an
unit cell the fermion spectrum splits into topological subbands with
well-defined Chern numbers, contains gapless edge modes in the gaps. It is
shown that the behavior of gapless edge modes is described within the framework
of the Kitaev chain where the tunneling of Majorana fermions is determined by
effective hopping of Majorana fermions between chains. The proposed approach
makes it possible to study the fermion spectrum in the case of an irrational
flux, to calculate the Hall conductance of subbands that form a fine structure
of the spectrum. In the case of a rational flux and a strong on-site Hubbard
interaction , ( is a gap), the topological state
of the system, which is determined by the corresponding Chern number and chiral
gapless edge modes, collapses. When the magnitude of the on-site Hubbard
interaction changes, at the point a topological phase
transition is realized, i.e., there are changes in the Chern numbers of two
subbands due to their degeneration.Comment: 7 pages, 5 figure
Nuclear multifragmentation and fission: similarity and differences
Thermal multifragmentation of hot nuclei is interpreted as the nuclear
liquid--fog phase transition deep inside the spinodal region. The experimental
data for p(8.1GeV) + Au collisions are analyzed. It is concluded that the decay
process of hot nuclei is characterized by two size parameters: transition state
and freeze-out volumes. The similarity between dynamics of fragmentation and
ordinary fission is discussed. The IMF emission time is related to the mean
rupture time at the multi-scission point, which corresponds to the kinetic
freeze-out configuration.Comment: 7 pages, 3 Postscript figures, Proceedings of IWM 2005, Catani
Exactly solvable model of topological insulator realized on spin-1/2 lattice
In this paper we propose an exactly solvable model of a topological insulator
defined on a spin-1/2 square decorated lattice. Itinerant fermions defined in
the framework of the Haldane model interact via the Kitaev interaction with
spin-1/2 Kitaev sublattice. The presented model, whose ground state is a
non-trivial topological phase, is solved exactly. We have found out that
various phase transitions without gap closing at the topological phase
transition point outline the separate states with different topological
numbers. We provide a detailed analysis of the model's ground-state phase
diagram and demonstrate how quantum phase transitions between topological
states arise. We have found that the states with both the same and different
topological numbers are all separated by the quantum phase transition without
gap closing. The transition between topological phases is accompanied by a
rearrangement of the spin subsystem's spectrum from band to flat-band states.Comment: 8 pages, 9 figure
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