Prediction of a surface state and a related surface insulator-metal transition for the (100) surface of stochiometric EuO

We calculate the temperature and layer-dependent electronic structure of a 20-layer EuO(100)-film using a combination of first-principles and model calculation based on the ferromagnetic Kondo-lattice model. The results suggest the existence of a EuO(100) surface state which can lead to a surface insulator-metal transition.Comment: 9 pages, 5 figures, Phys. Rev. Lett. (in press

Reply to ``Comment on `Test of constancy of speed of light with rotating cryogenic optical resonators' ''

An improved analysis of the Michelson-Morley-type experiment by P. Antonini et al. (Phys. Rev. A. 71, 050101 (2005)) yields the Robertson-Mansouri-Sexl theory parameter combination $\beta-\delta-1/2=(-0.6\pm 2.1\pm 1.2)\cdot10^{-10}$ and the Standard Model Extension theory parameter $(\tilde{\kappa}_{e-})^{ZZ} = (-2.9\pm 2.2)\cdot 10^{-14}$.Comment: 2 page

Scaling of Non-Perturbatively O(a) Improved Wilson Fermions: Hadron Spectrum, Quark Masses and Decay Constants

We compute the hadron mass spectrum, the quark masses and the meson decay constants in quenched lattice QCD with non-perturbatively $O(a)$ improved Wilson fermions. The calculations are done for two values of the coupling constant, $\beta = 6.0$ and 6.2, and the results are compared with the predictions of ordinary Wilson fermions. We find that the improved action reduces lattice artifacts as expected

Real-time dynamics in Quantum Impurity Systems: A Time-dependent Numerical Renormalization Group Approach

We develop a general approach to the nonequilibrium dynamics of quantum impurity systems for arbitrary coupling strength. The numerical renormalization group is used to generate a complete basis set necessary for the correct description of the time evolution. We benchmark our method with the exact analytical solution for the resonant-level model. As a first application, we investigate the equilibration of a quantum dot subject to a sudden change of the gate voltage and external magnetic field. Two distinct relaxation times are identified for the spin and charge dynamics.Comment: 5 pages, 5 figure

Projecting the Kondo Effect: Theory of the Quantum Mirage

A microscopic theory is developed for the projection (quantum mirage) of the Kondo resonance from one focus of an elliptic quantum corral to the other focus. The quantum mirage is shown to be independent of the size and the shape of the ellipse, and experiences \lambda_F/4 oscillations (\lambda_F is the surface-band Fermi wavelength) with an increasing semimajor axis length. We predict an oscillatory behavior of the mirage as a function of a weak magnetic field applied perpendicular to the sample.Comment: 4 pages 2 figures include

The SU(3) Beta Function from Numerical Stochastic Perturbation Theory

The SU(3) beta function is computed from Wilson loops to 20th order numerical stochastic perturbation theory. An attempt is made to include massless fermions, whose contribution is known analytically to 4th order. The question whether the theory admits an infrared stable fixed point is addressed.Comment: 10 pages, 7 figures, version to be published in Physics Letters

Photoemission study of the spin-density wave state in thin films of Cr

Angle-resolved photoemission (PE) was used to characterize the spin-density wave (SDW) state in thin films of Cr grown on W(110). The PE data were analysed using results of local spin density approximation layer-Korringa-Kohn-Rostoker calculations. It is shown that the incommensurate SDW can be monitored and important parameters of SDW-related interactions, such as coupling strength and energy of collective magnetic excitations, can be determined from the dispersion of the renormalized electronic bands close to the Fermi energy. The developed approach can readily be applied to other SDW systems including magnetic multilayer structures.Comment: 4 figure