Gauge symmetry and non-abelian topological sectors in a geometrically constrained model on the honeycomb lattice
(2006)
Density of quasiparticle states for a two-dimensional disordered system: Metallic, insulating, and critical behavior in the class D thermal quantum Hall effect
ArXiv cond-mat/0610700 (2006)
Abstract:
We investigate numerically the quasiparticle density of states $\varrho(E)$ for a two-dimensional, disordered superconductor in which both time-reversal and spin-rotation symmetry are broken. As a generic single-particle description of this class of systems (symmetry class D), we use the Cho-Fisher version of the network model. This has three phases: a thermal insulator, a thermal metal, and a quantized thermal Hall conductor. In the thermal metal we find a logarithmic divergence in $\varrho(E)$ as $E\to 0$, as predicted from sigma model calculations. Finite size effects lead to superimposed oscillations, as expected from random matrix theory. In the thermal insulator and quantized thermal Hall conductor, we find that $\varrho(E)$ is finite at E=0. At the plateau transition between these phases, $\varrho(E)$ decreases towards zero as $|E|$ is reduced, in line with the result $\varrho(E) \sim |E|\ln(1/|E|)$ derived from calculations for Dirac fermions with random mass.Analysis of trapped quantum degenerate dipolar excitons
Applied Physics Letters 89:15 (2006)
Abstract:
The dynamics of quantum degenerate two-dimensional dipolar excitons confined in electrostatic traps is analyzed and compared to recent experiments. The model results stress the importance of artificial trapping for achieving and sustaining a quantum degenerate exciton fluid in such systems and suggest that a long-lived, spatially uniform, and highly degenerate exciton system was experimentally produced in those electrostatic traps. © 2006 American Institute of Physics.The effect of optically-induced random anisotropic disorder on a two-dimensional electron system
Solid State Communications 140:2 (2006) 94-99