65,726 research outputs found
Size dependence of second-order hyperpolarizability of finite periodic chain under Su-Schrieffer-Heeger model
The second hyperpolarizability of
double-bond finite chain of trans-polyactylene is analyzed using the
Su-Schrieffer-Heeger model to explain qualitative features of the
size-dependence behavior of . Our study shows that is
{\it nonmonotonic} with and that the nonmonotonicity is caused by the
dominant contribution of the intraband transition to in polyenes.
Several important physical effects are discussed to reduce quantitative
discrepancies between experimental and our resultsComment: 3 figures, 1 tabl
Thermopower Oscillation Symmetries in a Double-Loop Andreev Interferrometer
Andreev interferometers, normal metal wires coupled to superconducting loops,
display phase coherent changes as the magnetic flux through the superconducting
loops is altered. Properties such as the electronic and thermal conductance of
these devices have been shown to oscillate symmetrically about zero with a
period equal to one superconducting flux quantum, . However, the
thermopower of these devices can oscillate symmetrically or antisymmetrically
depending on the geometry of the sample, a phenomenon not well understood
theoretically. Here we report on thermopower measurements of a double-loop
Andreev interferometer where two Josephson currents in the normal metal wire
may be controlled independently. The amplitude and symmetries of the observed
thermopower oscillations may help to illuminate the unexplained dependence of
oscillation symmetry on sample geometry.Comment: 6 Pages, 5 figures, to appear in Physica
Varieties with vanishing holomorphic Euler characteristic
International audienceAbstract. We study smooth complex projective varietie
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