199 research outputs found
Transport properties of nanosystems with conventional and unconventional charge density waves
We report a systematic study of transport properties of nanosytems with
charge density waves. We demonstrate, how the presence of density waves
modifies the current-voltage characteristics. On the other hand hand, we show
that the density waves themselves are strongly affected by the applied voltage.
This self-consistent problem is solved within the formalism of the
nonequilibrium Green functions. The conventional charge density waves occur
only for specific, periodically distributed ranges of the voltage. Apart from
the low voltage regime, they are incommensurate and the corresponding wave
vectors decrease discontinuously when the voltage increases.Comment: 7 pages, 7 figures, revte
Coexistence of Anomalous and Normal Diffusion in Integrable Mott Insulators
We study the finite-momentum spin dynamics in the one-dimensional XXZ spin
chain within the Ising-type regime at high temperatures using density
autocorrelations within linear response theory and real-time propagation of
nonequilibrium densities. While for the nonintegrable model results are well
consistent with normal diffusion, the finite-size integrable model unveils the
coexistence of anomalous and normal diffusion in different regimes of time. In
particular, numerical results show a Gaussian relaxation at smallest nonzero
momenta which we relate to nonzero stiffness in a grand canonical ensemble. For
larger but still small momenta normal-like diffusion is recovered. Similar
results for the model of impenetrable particles also help to resolve rather
conflicting conclusions on transport in integrable Mott insulators.Comment: 5 pages, 4 figure
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