5,711 research outputs found
Thermal transport properties of disordered spin-1/2 systems
This work studies heat transport of bond-disordered spin-1/2 chains. As an
example, the XX case is analyzed, which corresponds to a model of
noninteracting spinless fermions. Within the fermion representation, the
single-particle eigenenergies are determined numerically, which allow one to
compute transport coefficients. Since the ballistic transport properties of a
clean chain are destroyed by disorder, the focus is on the frequency dependence
of the thermal conductivity and on a qualitative comparison with the spin
conductivity, both at finite temperatures.Comment: 2 pages, 1 figure. To be published in the Proceedings of SCES '05,
Vienna, in Physica
Transport in dimerized and frustrated spin systems
We analyze the Drude weight for both spin and thermal transport of
one-dimensional spin-1/2 systems by means of exact diagonalization at finite
temperatures. While the Drude weights are non-zero for finite systems, we find
indications of a vanishing of the Drude weights in the thermodynamic limit for
non-integrable models implying normal transport behavior.Comment: 2 pages, 1 figure. Proceedings of the ICM 2003, Rom
Quantum phases of strongly-interacting bosons on a two-leg Haldane ladder
We study the ground-state physics of a single-component Haldane model on a
hexagonal two-leg ladder geometry with a particular focus on strongly
interacting bosonic particles. We concentrate our analysis on the regime of
less than one particle per unit-cell. As a main result, we observe several
Meissner-like and vortex-fluid phases both for a superfluid as well as a
Mott-insulating background. Furthermore, we show that for strongly interacting
bosonic particles an unconventional vortex-lattice phase emerges, which is
stable even in the regime of hardcore bosons. We discuss the mechanism for its
stabilization for finite interactions by a means of an analytical
approximation. We show how the different phases may be discerned by measuring
the nearest- and next-nearest-neighbor chiral currents as well as their
characteristic momentum distributions.Comment: 13 pages, 20 figure
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