68,492 research outputs found
Mode-locking of incommensurate phase by quantum zero point energy in the Frenkel-Kontorova model
In this paper, it is shown that a configuration modulated system described by
the Frenkel-Kontorova model can be locked at an incommensurate phase when the
quantum zero point energy is taken into account. It is also found that the
specific heat for an incommensurate phase shows different parameter-dependence
in sliding phase and pinning phase. These findings provide a possible way for
experimentalists to verify the phase transition by breaking of analyticity.Comment: 6 pages in Europhys style, 3 eps figure
Free-energy barrier to melting of single-chain polymer crystallite
We report Monte Carlo simulations of the melting of a single-polymer
crystallite. We find that, unlike most atomic and molecular crystals, such
crystallites can be heated appreciably above their melting temperature before
they transform to the disordered "coil" state. The surface of the superheated
crystallite is found to be disordered. The thickness of the disordered layer
increases with superheating. However, the order-disorder transition is not
gradual but sudden. Free-energy calculations reveal the presence of a large
free-energy barrier to melting.Comment: AMS-Latex, 4 pages with 5 figures, submitted to Phys. Rev. Let
Coexistence and competition of multiple charge-density-wave orders in rare-earth tri-telluride RTe3
The occurrences of collective quantum states, such as superconductivity (SC)
and charge- or spin-densitywaves (CDWs or SDWs), are among the most fascinating
phenomena in solids. To date much effort has been made to explore the interplay
between different orders, yet little is known about the relationship of
multiple orders of the same type. Here we report optical spectroscopy study on
CDWs in the rare-earth tri-telluride compounds RTe3 (R = rare earth elements).
Besides the prior reported two CDW orders, the study reveals unexpectedly the
presence of a third CDW order in the series which evolves systematically with
the size of R element. With increased chemical pressure, the first and third
CDW orders are both substantially suppressed and compete with the second one by
depleting the low energy spectral weight. A complete phase diagram for the
multiple CDW orders in this series is established.Comment: 7 pages, 4 figures, 1 tabl
Leggett mode in a strong-coupling model of iron arsenide superconductors
Using a two-orbital model of the superconducting phase of the pnictides, we
compute the spectrum of the Leggett mode -- a collective excitation of the
phase of the superconducting gap known to exist in multi-gap superconductors --
for different possible symmetries of the superconducting order parameter.
Specifically, we identify the small regions of parameter space where the
Leggett mode lies below the two-particle continuum, and hence should be visible
as a sharp resonance peak. We discuss the possible utility of the Leggett mode
in distinguishing different momentum dependencies of the superconducting gap.
We argue that the observation of a sharp Leggett mode would be consistent with
the presence of strong electron-electron correlations in iron-based
superconductors. We also emphasize the importance of the orbital character of
the Leggett mode, which can result in an experimental observation of the mode
in channels other than
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