Schedule Aug 19, 2003
Depinning of Driven Systems: Time-resolved x-ray scattering measurements of the charge-density waves in NbSe3
Joel Brock (Cornell University)

Extended condensed matter systems driven over quenched random disorder exhibit diverse phenomena, including nonequilibrium phase transitions and history dependence. Examples of such systems include vortex arrays in type-II superconductors and charge-density waves (CDWs) in anisotropic metals. Using several synchrotron-based x-ray techniques, we have studied the structure of driven CDWs in the quasi one-dimensional metal NbSe3. The data clearly demonstrate that models based on the dissipative dynamics of driven elastic media are unable to describe the CDW problem accurately[1-4]. Two new descriptions capture some of the relevant physics. The first considers a viscoelastic medium[5], in which elastic couplings are replaced by couplings that are non-local in time. The second is based on a modified Swift-Hohenberg equation[6], which includes both amplitude and phase fluctuations of the condensate.


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