1,062 research outputs found
Carrier-controlled ferromagnetism in SrTiO3
Magnetotransport and superconducting properties are investigated for
uniformly La-doped SrTiO3 films and GdTiO3/SrTiO3 heterostructures,
respectively. GdTiO3/SrTiO3 interfaces exhibit a high-density two-dimensional
electron gas on the SrTiO3-side of the interface, while for the SrTiO3 films
carriers are provided by the dopant atoms. Both types of samples exhibit
ferromagnetism at low temperatures, as evidenced by a hysteresis in the
magnetoresistance. For the uniformly doped SrTiO3 films, the Curie temperature
is found to increase with doping and to coexist with superconductivity for
carrier concentrations on the high-density side of the superconducting dome.
The Curie temperature of the GdTiO3/SrTiO3 heterostructures scales with the
thickness of the SrTiO3 quantum well. The results are used to construct a
stability diagram for the ferromagnetic and superconducting phases of SrTiO3.Comment: Revised version that is closer to the published version; Fig. 2
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Effects of radiative heat transfer on the structure of turbulent supersonic channel flow
International audienceThe interaction between turbulence in a minimal supersonic channel and radiative heat transfer is studied using large-eddy simulation. The working fluid is pure water vapour with temperature-dependent specific heats and molecular transport coefficients. Its line spectra properties are represented with a statistical narrow-band correlated-k model. A grey gas model is also tested. The parallel no-slip channel walls are treated as black surfaces concerning thermal radiation and are kept at a constant temperature of 1000 K. Simulations have been performed for different optical thicknesses (based on the Planck mean absorption coefficient) and different Mach numbers. Results for the mean flow variables, Reynolds stresses and certain terms of their transport equations indicate that thermal radiation effects counteract compressibility (Mach number) effects. An analysis of the total energy balance reveals the importance of radiative heat transfer, compared to the turbulent and mean molecular heat transport
Dynamics of Competitive Evolution on a Smooth Landscape
We study competitive DNA sequence evolution directed by {\it in vitro}
protein binding. The steady-state dynamics of this process is well described by
a shape-preserving pulse which decelerates and eventually reaches equilibrium.
We explain this dynamical behavior within a continuum mean-field framework.
Analytical results obtained on the motion of the pulse agree with simulations.
Furthermore, finite population correction to the mean-field results are found
to be insignificant.Comment: 4 pages, 2 figures, revised, to appear in Phys. Rev. Let
Separation of transport lifetimes in SrTi
Deviations from Landau Fermi liquid behavior are ubiquitous features of the
normal state of unconventional superconductors. Despite several decades of
investigation, the underlying mechanisms of these properties are still not
completely understood. In this work, we show that two-dimensional electron
liquids at SrTiO3/RTiO3 (R = Gd or Sm) interfaces reveal strikingly similar
physics. Analysis of Hall and resistivity data show a clear separation of
transport and Hall scattering rates, also known as "two-lifetime" behavior.
This framework gives a remarkably simple and general description of the
temperature dependence of the Hall coefficient. Distinct transport lifetimes
accurately describe the transport phenomena irrespective of the nature of
incipient magnetic ordering, the degree of disorder, confinement, or the
emergence of non-Fermi liquid behavior. The Hall scattering rate diverges at a
critical quantum well thickness, coinciding with a quantum phase transition.
Collectively, these results introduce new constraints on the existing
microscopic theories of lifetime separation and point to the need for unified
understanding.Comment: Version accepted for publication in Phys. Rev.
Unusual coloration of a Hairy woodpecker from Oregon
Northwestern Naturalist does not hold copyright on any articles or notes published in the journal. The attached file is the published version of the article. If you wish to consult the rest of the issue visit the publisher's website
Analytical study of the effect of recombination on evolution via DNA shuffling
We investigate a multi-locus evolutionary model which is based on the DNA
shuffling protocol widely applied in \textit{in vitro} directed evolution. This
model incorporates selection, recombination and point mutations. The simplicity
of the model allows us to obtain a full analytical treatment of both its
dynamical and equilibrium properties, for the case of an infinite population.
We also briefly discuss finite population size corrections
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