Charge-density-wave phase slip and contact effects in NbSe3

Measurement of the shear strength of a charge density wave

We have explored the shear plasticity of charge density waves (CDWs) in NbSe3 samples with cross sections having a single microfabricated thickness step. Shear stresses along the step result from thickness-dependent CDW pinning. For small thickness differences the CDW depins elastically at the volume average depinning field. For large thickness differences the thicker, more weakly pinned side depins first via plastic shear, and shear plasticity contributes substantial dissipation well above the depinning field. A simple model describes the qualitative features of our data and yields a value for the CDW's shear strength of approximately 9.5 x 10(3) Nm(-2). This value is orders of magnitude smaller than the CDW's longitudinal modulus but much larger than corresponding values for flux line lattices, and in part explains the relative coherence of the CDW response.

Tunable charge-density wave transport in a current-effect transistor

The collective charge-density wave (CDW) conduction is modulated by a transverse single-particle current in a transistorlike device. Nonequilibrium conditions in this geometry lead to an exponential reduction of the depinning threshold, allowing the CDWs to slide at much lower bias fields. The results are in excellent agreement with a recently proposed dynamical model in which "wrinkles" in the CDW wave fronts are "ironed" by the transverse current. The experiment might have important implications for other driven periodic media, such as moving vortex lattices or "striped phases" in high- T(c) superconductors.

Charge-density-wave current conversion in submicron NbSe3 wires

We have studied the charge-density-wave (CDW) current conversion process in NbSe3 wire structures of mesoscopic dimensions. A significant reduction of the phase-slip voltage associated with this conversion is observed if the spacing between current contacts is smaller than a few &mgr;m. This reduction cannot be explained with existing models of CDW current conversion. We suggest that single phase-slip events play a central role in micron-sized systems. The removal and addition of wave fronts may then become correlated in time.