32,679 research outputs found
Level-One Representations and Vertex Operators of Quantum Affine Superalgebra
Level-one representations of the quantum affine superalgebra
associated to the appropriate non-standard system of
simple roots and -vertex operators (intertwining operators) associated with
the level-one modules are constructed explicitly in terms of free bosonic
fields.Comment: Errors in the cocycle factors of the vertex operators and some typos
are corrected. LaTex file 17 page
Prediction of thickness limits of ideal polar ultrathin films
Competition between electronic and atomic reconstruction is a constantly
recurring theme in transition-metal oxides. We use density functional theory
calculations to study this competition for a model system consisting of a thin
film of the polar, infinite-layer structure ACuO2 (A=Ca, Sr, Ba) grown on a
nonpolar, perovskite SrTiO3 substrate. A transition from the bulk planar
structure to a chain-type thin film accompanied by substantial changes to the
electronic structure is predicted for a SrCuO2 film fewer than five unit cells
thick. An analytical model explains why atomic reconstruction becomes more
favorable than electronic reconstruction as the film becomes thinner, and
suggests that similar considerations should be valid for other polar films
Quantum Affine Lie Algebras, Casimir Invariants and Diagonalization of the Braid Generator
Let be an infinite-dimensional quantum affine Lie
algebra. A family of central elements or Casimir invariants are constructed and
their eigenvalues computed in any integrable irreducible highest weight
representation. These eigenvalue formulae are shown to absolutely convergent
when the deformation parameter is such that . It is proven that the
universal R-matrix of satisfies the celebrated
conjugation relation with the usual twist map. As
applications, the braid generator is shown to be diagonalizable on arbitrary
tensor product modules of integrable irreducible highest weight -modules and a spectral decomposition formula for the braid generator is
obtained which is the generalization of Reshetikhin's and Gould's forms to the
present affine case. Casimir invariants acting on a specified module are also
constructed and their eigenvalues, again absolutely convergent for ,
computed by means of the spectral decomposition formula.Comment: 22 pages (many changes are made
Supersymmetric Vertex Models with Domain Wall Boundary Conditions
By means of the Drinfeld twists, we derive the determinant representations of
the partition functions for the and supersymmetric vertex
models with domain wall boundary conditions. In the homogenous limit, these
determinants degenerate to simple functions.Comment: 19 pages, 4 figures, to be published in J. Math. Phy
Stable and highly sensitive gas sensors based on semiconducting oxide nanobelts
©2002 American Institute of Physics. The electronic version of this article is the complete one and can be found online at: : http://link.aip.org/link/?APPLAB/81/1869/1DOI:10.1063/1.1504867Gas sensors have been fabricated using the single-crystalline SnO₂ nanobelts. Electrical
characterization showed that the contacts were ohmic and the nanobelts were sensitive to
environmental polluting species like CO and NO₂ , as well as to ethanol for breath analyzers and
food control applications. The sensor response, defined as the relative variation in conductance due
to the introduction of the gas, is 4160% for 250 ppm of ethanol and 21550% for 0.5 ppm NO₂ at
400 °C. The results demonstrate the potential of fabricating nanosized sensors using the integrity of
a single nanobelt with a sensitivity at the level of a few ppb
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