The density of states and the Hall conductivity of a two-dimensional electron gas in a uniform magnetic field and in the presence of a δ-impurity are exactly calculated using elementary field theoretic techniques. The impurity creates one localized state per Landau level, but the Hall conductivity is unaffected. Our treatment is explicitly gauge-invariant, and can be easily adapted to other pro...

The goal of this paper is to provide an intuitive and useful tool for analyzing the impurity bound state problem. We develop a semiclassical approach and apply it to an impurity in two dimensional systems with parabolic or Dirac like bands. Our method consists of reducing a higher dimensional problem into a sum of one dimensional ones using the two dimensional Green functions as a guide. We the...

The difference of temperatures between an impurity and the surrounding gas in an open vibrated granular system is studied. It is shown that, in spite of the high inhomogeneity of the state, the temperature ratio remains constant in the bulk of the system. The lack of energy equipartition is associated to the change of sign of the pressure diffusion coefficient for the impurity at certain values...

Transport in an ideal two-dimensional quantum spin Hall device is dominated by the counterpropagating edge states of electrons with opposite spins, giving the universal value of the conductance, 2e(2)/h. We study the effect on the conductance of a magnetic impurity, which can backscatter an electron from one edge state to the other. In the case of isotropic Kondo exchange we find that the corre...

We study the electronic structure of magnetic and nonmagnetic quantum corrals embedded in two-dimensional s-wave superconductors. We demonstrate that a quantum mirage of an impurity bound state is projected from the occupied into the empty focus of a nonmagnetic quantum corral via the excitation of the corral's eigenmodes. We show that quantum corrals provide a new tool for manipulating the int...

The randomness of dopant atom distributions in cuprate high-critical temperature superconductors has long been suspected to cause nanoscale electronic disorder. In the superconductor Bi2Sr2CaCu2O8+delta, we identified populations of atomic-scale impurity states whose spatial densities follow closely those of the oxygen dopant atoms. We found that the impurity-state locations are strongly correl...

The low-energy properties of the Anderson impurity are studied under a finite bias voltage V using the perturbation theory in U of Yamada and Yosida in the nonequilibrium Keldysh diagrammatic formalism. The self-energy is calculated exactly up to terms of order ω, T 2 and V 2 using Ward identities. The coefficients are defined with respect to the equilibrium ground state, and contain all contri...

We investigate a tunable two-impurity Kondo system in a strongly correlated carbon nanotube double quantum dot, accessing the full range of charge regimes. In the regime where both dots contain an unpaired electron, the system approaches the two-impurity Kondo model. At zero magnetic field the interdot coupling disrupts the Kondo physics and a local singlet state arises, but we are able to tune...

(Received) Scattering by a single impurity introduced in a strongly correlated electronic system is studied by exact diagonalization of small clusters. It is shown that an inert site which is spinless and unable to accomodate holes can give rise to strong resonant scattering. A calculation of the local density of state reveals that, for increasing antiferromagnetic exchange coupling, d, s and p...

The appropriate generalization of the isotropic impurity Anderson model for va-lence fluctuations between two magnetic multiplets l n and l n+1 is solved in the strong-coupling limit of Wilson's renormalization group for l ≤ 3. Except in the extreme case of j − j coupling, the ground state is degenerate, the impurity magnetic moment is very small and is overscreened by the conduction electrons....