Effects of rotation and magnetic field on the onset of convective instability in a liquid layer due to buoyancy and surface tension

Thermocapillary stability characteristics of a horizontal liquid layer heated from below rotating about a vertical axis and subjected to a uniform vertical magnetic field are analyzed under a variety of thermal and electromagnetic boundary conditions. Results based on analytical solutions to the pertinent eigenvalue problems are discussed in the light of earlier work on special cases of the more general problem considered here to show in particular the effects of the heat transfer, nonzero curvature and gravity waves at the two-fluid interface. Although the expected stabilizing action of the Coriolis and Lorentz force fields in this configuration are in evidence the optimal choice of an appropriate range for the relevant parameters is shown to be critically dependent on the interfacial effects mentioned above

Carrier relaxation due to electron-electron interaction in coupled double quantum well structures

We calculate the electron-electron interaction induced energy-dependent inelastic carrier relaxation rate in doped semiconductor coupled double quantum well nanostructures within the two subband approximation at zero temperature. In particular, we calculate, using many-body theory, the imaginary part of the full self-energy matrix by expanding in the dynamically RPA screened Coulomb interaction, obtaining the intrasubband and intersubband electron relaxation rates in the ground and excited subbands as a function of electron energy. We separate out the single particle and the collective excitation contributions, and comment on the effects of structural asymmetry in the quantum well on the relaxation rate. Effects of dynamical screening and Fermi statistics are automatically included in our many body formalism rather than being incorporated in an ad-hoc manner as one must do in the Boltzman theory.Comment: 26 pages, 5 figure

Film-stability in a vertical rotating tube with a core-gas flow

Linear hydrodynamic stability of interface between Newtonian liquid film and core fluid under influence of swirl, core flow, and gravit

Spectral functions in doped transition metal oxides

We present experimental photoemission and inverse photoemission spectra of SrTiO$_{3- \delta}$ representing electron doped $d^0$ systems. Photoemission spectra in presence of electron doping exhibit prominent features arising from electron correlation effects, while the inverse photoemssion spectra are dominated by spectral features explainable within single-particle approaches. We show that such a spectral evolution in chemically doped correlated systems is not compatible with expectations based on Hubbard or any other similar model. We present a new theoretical approach taking into account the inhomogeneity of the `real' system which gives qualitatively different results compared to standard `homogeneous' models and is in quantitative agreement with experiments.Comment: 10 pages; 1 tex file+4 postscript files (to appear in Europhysics Letters

Dissipationless transport in low density bilayer systems

In a bilayer electronic system the layer index may be viewed as the z-component of an isospin-1/2. An XY isospin-ordered ferromagnetic phase was observed in quantum Hall systems and is predicted to exist at zero magnetic field at low density. This phase is a superfluid for opposite currents in the two layers. At B=0 the system is gapless but superfluidity is not destroyed by weak disorder. In the quantum Hall case, weak disorder generates a random gauge field which probably does not destroy superfluidity. Experimental signatures include Coulomb drag and collective mode measurements.Comment: 4 pages, no figures, submitted to Phys. Rev. Let

Extended Self-similarity in Kinetic Surface Roughening

We show from numerical simulations that a limited mobility solid-on-solid model of kinetically rough surface growth exhibits extended self-similarity analogous to that found in fluid turbulence. The range over which scale-independent power-law behavior is observed is significantly enhanced if two correlation functions of different order, such as those representing two different moments of the difference in height between two points, are plotted against each other. This behavior, found in both one and two dimensions, suggests that the `relative' exponents may be more fundamental than the `absolute' ones.Comment: 4 pages, 4 postscript figures included (some changes made according to referees' comments. accepted for publication in PRE Rapid Communication

Band gap renormalization in photoexcited semiconductor quantum wire structures in the GW approximation

We investigate the dynamical self-energy corrections of the electron-hole plasma due to electron-electron and electron-phonon interactions at the band edges of a quasi-one dimensional (1D) photoexcited electron-hole plasma. The leading-order $GW$ dynamical screening approximation is used in the calculation by treating electron-electron Coulomb interaction and electron-optical phonon Fr\"{o}hlich interaction on an equal footing. We calculate the exchange-correlation induced band gap renormalization (BGR) as a function of the electron-hole plasma density and the quantum wire width. The calculated BGR shows good agreement with existing experimental results, and the BGR normalized by the effective quasi-1D excitonic Rydberg exhibits an approximate one-parameter universality.Comment: 11 pages, 3 figure

Spin transport in inhomogeneous magnetic fields: a proposal for Stern-Gerlach-like experiments with conduction electrons

Spin dynamics in spatially inhomogeneous magnetic fields is studied within the framework of Boltzmann theory. Stern-Gerlach-like separation of spin up and spin down electrons occurs in ballistic and diffusive regimes, before spin relaxation sets in. Transient dynamics and spectral response to time-dependent inhomogeneous magnetic fields are investigated, and possible experimental observations of our findings are discussed.Comment: 7 pages, 4 figures; revised and extended version, to appear in PR

Hall state quantization in a rotating frame

We derive electromagnetomotive force fields for charged particles moving in a rotating Hall sample, satisfying a twofold U(1) gauge invariance principle. It is then argued that the phase coherence property of quantization of the line integral of total collective particle momentum into multiples of Planck's quantum of action is solely responsible for quantization in the Hall state. As a consequence, the height of the Hall quantization steps should remain invariant in a rapidly rotating Hall probe. Quantum Hall particle conductivities do not depend on charge and mass of the electron, and are quantized in units of the inverse of Planck's action quantum.Comment: 6 pages, accepted for publication in Europhysics Letter