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# Search results

91 records were found.

## The surface states of topological insulators - Dirac fermion in curved two dimensional spaces

The surface of a topological insulator is a closed two dimensional manifold. The surface states are described by the Dirac Hamiltonian in curved two dimensional spaces. For a slab-like sample with a magnetic field perpendicular to its top and bottom surfaces, there are chiral states delocalized on the four side faces. These "chiral sheets" carry both charge and spin currents. In strong magnetic fields the quantized charge Hall effect ($\s_{xy}=(2n+1)e^2/h$) will coexist with spin Hall effect.

## The effects of interaction on quantum spin Hall insulators

Comment: 4 pages, 4 figures

## A Duality Between Unidirectional Charge Density Wave Order and Superconductivity

Comment: Main results are the same, but the presentation is significantly modified. To appear in Physical Review Letters

## Inhomogeneity in doped Mott insulator

Comment: Talk given at MOS2002

## Network Models of Quantum Percolation and Their Field-Theory Representations

Comment: 11 pages, LaTeX

## Network Models of Quantum Percolation and Their Field-Theory Representations

We obtain the field-theory representations of several network models that are relevant to 2D transport in high magnetic fields. Among them, the simplest one, which is relevant to the plateau transition in the quantum Hall effect, is equivalent to a particular representation of an antiferromagnetic SU(2N) ($N\to 0$) spin chain. Since the later can be mapped onto a $\theta\ne 0$, $U(2N)/U(N)\times U(N)$ sigma model, and since recent numerical analyses of the corresponding network give a delocalization transition with $\nu\approx 2.3$, we conclude that the same exponent is applicable to the sigma model.

## Neutral Fermions at $\nu=1/2$

Comment: An error in Eq.(11) is corrected

## An Unsettled Issue in the Theory of the Half-Filled Landau Level

The purpose of this paper is to identify an unsettled issue in the theory of the half-filled Landau level, and state our point of view.

## Pairing via Index theorem

This work is motivated by a specific point of view: at short distances and high energies the undoped and underdoped cuprates resemble the $\pi$-flux phase of the t-J model. The purpose of this paper is to present a mechanism by which pairing grows out of the doped $\pi$-flux phase. According to this mechanism pairing symmetry is determined by a parameter controlling the quantum tunneling of gauge flux quanta. For zero tunneling the symmetry is $d_{x^2-y^2}+id_{xy}$, while for large tunneling it is $d_{x^2-y^2}$. A zero-temperature critical point separates these two limits.