PACS. 71.45.Lr Charge-density-wave systems – 72.15.Nj Collective modes (e.g., in one-dimensional conductors) – 62.30.+d Mechanical and elastic waves; vibrations – 62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
Springer Online Journal Archives 1860-2000
Abstract: We report on measurements of the voltage dependence of the complex shear compliance of two crystals of the charge-density-wave (CDW) conductor NbSe3, for torsional frequencies between 1 Hz and 71 Hz. For both samples, there is a frequency independent, ∼1% increase of the magnitude of the compliance when the voltage exceeds the threshold for CDW depinning, but the internal friction has a striking sample dependence which we do not understand. For one sample, there is a frequency independent decrease in internal friction with CDW depinning, suggesting that the elastic changes are not relaxational and might reflect changes in the screening of the crystal strain by the CDW. For the second sample, the sign and magnitude of the change in internal friction is strongly frequency dependent, which we associate with a change in screening due to the finite electron diffusion time. The second sample also exhibits a frequency dependent peak in internal friction near threshold that may reflect relaxation of the CDW phase.
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