Current and vorticity auto correlation functions in open microwave billiards

Using the equivalence between the quantum-mechanical probability density in a quantum billiard and the Poynting vector in the corresponding microwave system, current distributions were studied in a quantum dot like cavity, as well as in a Robnik billiard with lambda=0.4, and an introduced ferrite cylinder. Spatial auto correlation functions for currents and vorticity were studied and compared with predictions from the random-superposition-of-plane-waves hypothesis. In addition different types of vortex neighbour spacing distributions were determined and compared with theory.Comment: PTP-LaTeX, 10 pages with 6 figures submitted to Progress of Theoretical Physics Supplemen

Electron Removal Self Energy and its application to Ca2CuO2Cl2

We propose using the self energy defined for the electron removal Green's function. Starting from the electron removal Green's function, we obtained expressions for the removal self energy Sigma^ER (k,omega) that are applicable for non-quasiparticle photoemission spectral functions from a single band system. Our method does not assume momentum independence and produces the self energy in the full k-omega space. The method is applied to the angle resolved photoemission from Ca_2CuO_2Cl_2 and the result is found to be compatible with the self energy value from the peak width of sharp features. The self energy is found to be only weakly k-dependent. In addition, the Im Sigma shows a maximum at around 1 eV where the high energy kink is located.Comment: 5 pages, 3 figure

Kinetic stabilization of Fe film on (4 by 2)-GaAs(100)

We grow Fe film on (4 by 2)-GaAs(100) at low temperature, (~ 130 K) and study their chemical structure by photoelectron spectroscopy using synchrotron radiation. We observe the effective suppression of As segregation and remarkable reduction of alloy formation near the interface between Fe and substrate. Hence, this should be a way to grow virtually pristine Fe film on GaAs(100). Further, the Fe film is found stable against As segregation even after warmed up to room temperature. There only forms very thin, ~ 8 angstrom thick interface alloy. It is speculated that the interface alloy forms via surface diffusion mediated by interface defects formed during the low temperature growth of the Fe film. Further out-diffusion of both Ga and As are suppressed because it should then proceed via inefficient bulk diffusion.Comment: 4 figure

Spin polarization of light atoms in jellium: Detailed electronic structures

We revisit the problem of the spontaneous magnetization of an {\em sp} impurity atom in a simple metal host. The main features of interest are: (i) Formation of the spherical spin density/charge density wave around the impurity; (ii) Considerable decrease in the size of the pseudoatom in the spin-polarized state as compared with the paramagnetic one, and (iii) Relevance of the electron affinity of the isolated atom to this spin polarization, which is clarified by tracing the transformation of the pseudoatom into an isolated negative ion in the low-density limit of the enveloping electron gas.Comment: 4 pages, 4 figures, accepted to Phys. Rev.

Inflation with blowing-up solution of cosmological constant problem

The cosmological constant problem is how one chooses, without fine-tuning, one singular point $\Lambda_{eff}=0$ for the 4D cosmological constant. We argue that some recently discovered {\it weak self-tuning} solutions can be viewed as blowing-up this one point into a band of some parameter. These weak self-tuning solutions may have a virtue that only de Sitter space solutions are allowed outside this band, allowing an inflationary period. We adopt the hybrid inflation at the brane to exit from this inflationary phase and to enter into the standard Big Bang cosmology.Comment: LaTeX file of 20 pages including 2 eps figure

Local Hall effect in hybrid ferromagnetic/semiconductor devices

We have investigated the magnetoresistance of ferromagnet-semiconductor devices in an InAs two-dimensional electron gas system in which the magnetic field has a sinusoidal profile. The magnetoresistance of our device is large. The longitudinal resistance has an additional contribution which is odd in applied magnetic field. It becomes even negative at low temperature where the transport is ballistic. Based on the numerical analysis, we confirmed that our data can be explained in terms of the local Hall effect due to the profile of negative and positive field regions. This device may be useful for future spintronic applications.Comment: 4 pages with 4 fugures. Accepted for publication in Applied Physics Letter

Signatures of Dynamical Tunneling in the Wave function of a Soft-Walled Open Microwave Billiard

Evidence for dynamical tunneling is observed in studies of the transmission, and wave functions, of a soft-walled microwave cavity resonator. In contrast to previous work, we identify the conditions for dynamical tunneling by monitoring the evolution of the wave function phase as a function of energy, which allows us to detect the tunneling process even under conditions where its expected level splitting remains irresolvable.Comment: 5 pages, 5 figure