3,997 research outputs found

    Novel duality in disorder driven local quantum criticality

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    We find that competition between random Kondo and random magnetic correlations results in a quantum phase transition from a local Fermi liquid to a spin liquid. The local charge susceptibility turns out to have exactly the same critical exponent as the local spin susceptibility, suggesting novel duality between the Kondo singlet phase and the critical local moment state beyond the Landau-Ginzburg-Wilson symmetry breaking framework. This leads us to propose an enhanced symmetry at the local quantum critical point, described by an O(4) vector for spin and charge. The symmetry enhancement serves mechanism of electron fractionalization in critical impurity dynamics, where such fractionalized excitations are identified with topological excitations

    On direction of spontaneous magnetization in a "cubic" ferromagnet

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    The magnetic properties of anisotropic films have been studied using 3D-neutron polarization analysis. The experimental facts refer to essential distinction of the sample states, magnetized in opposite directions. For an explanation of asymmetrical effects the model is offered, in which the fundamental theoretical principles of structural phase transitions are used.Comment: 4 pages LaTeX (phbauth) and 4 figures (epsfig

    Small T1−1T_1^{-1} coherence peak near TcT_c in unconventional superconductors

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    It is usually believed that a coherence peak just below Tc_{c} in the nuclear spin lattice relaxation rate T1−1_{1}^{-1} in superconducting materials is a signature of conventional s-wave pairing. In this paper we demonstrate that any unconventional superconductor obeying BCS pure-case weak-coupling theory should show a small T1−1_{1}^{-1} coherence peak near Tc_{c}, generally with a height between 3 and 15 percent greater than the normal state T1−1_{1}^{-1} at Tc_{c}. It is largely due to impurity effects that this peak has not commonly been observed.Comment: 4 pages, 5 figure

    Exponential suppression of thermal conductance using coherent transport and heterostructures

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    We consider coherent thermal conductance through multilayer photonic crystal heterostructures, consisting of a series of cascaded non-identical photonic crystals. We show that thermal conductance can be suppressed exponentially with the number of cascaded crystals, due to the mismatch between photonic bands of all crystals in the heterostructure.Comment: 15 pages, 4 figure

    Ultramicrobacteria Genome Database Project

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    Ultramicrobacteria (UMB) are a largely uncultured, globally abundant, and metabolically active group of bacteria. UMB have cell diameters ≤0.3μm, cell volumes ≤0.1 μm3, and small streamlined genomes. Recent findings indicate that UMB aid in bioremediation and nutrient cycling, but future investigations and comprehension of current findings are skewed by highly variable nomenclature and a lack of databases for functional, genomic, geochemical, or spatial data specific to candidate UMB. We aim to develop a user-friendly open-access database of various UMB candidates linked to an open-access online map where researchers can gather genomic, spatial, and geochemical data. Our comprehensive review of literature and genomic databases revealed several mis-identified UMB candidates, unique highly-conserved fermentation pathways, and novel membrane proteins. We are actively updating this resource and working to link this database to the K-base bioinformatics platform on the Oak Ridge National Laboratory Supercomputer. This database is one of the first steps towards further investigations of the function, structure, and potential biotechnical applications of UMB

    Inferring periodic orbits from spectra of simple shaped micro-lasers

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    Dielectric micro-cavities are widely used as laser resonators and characterizations of their spectra are of interest for various applications. We experimentally investigate micro-lasers of simple shapes (Fabry-Perot, square, pentagon, and disk). Their lasing spectra consist mainly of almost equidistant peaks and the distance between peaks reveals the length of a quantized periodic orbit. To measure this length with a good precision, it is necessary to take into account different sources of refractive index dispersion. Our experimental and numerical results agree with the superscar model describing the formation of long-lived states in polygonal cavities. The limitations of the two-dimensional approximation are briefly discussed in connection with micro-disks.Comment: 13 pages, 19 figures, accepted for publication in Physical Review

    Predictions of the total emissivity of metals at cryogenic temperatures

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    Total emissivity predictions of metals at cryogenic temperature
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