Physics Commons^™

Interface Motion In Random Media At Finite Temperature, Lee-Wen Chen, M. Cristina Marchetti

Physics - All Scholarship

We have studied numerically the dynamics of a driven elastic interface in a random medium, focusing on the thermal rounding of the depinning transition and on the behavior in the

T = 0 pinned phase. Thermal effects are quantitatively more important than expected from simple dimensional estimates. For sufficient low temperature the creep velocity at a driving force equal to the T = 0 depinning force exhibits a power-law dependence on T, in agreement with earlier theoretical and numerical predictions for CDW’s. We have also examined the dynamics in the T = 0 pinned phase resulting from slowly increasing the …

Low-Temperatures Vortex Dynamics In Twinned Superconductors, M. Cristina Marchetti, Valerii M. Vinokur

Physics - All Scholarship

We discuss the low-temperature dynamics of magnetic flux lines in samples with a family of parallel twin planes. A current applied along the twin planes drives flux motion in the direction transverse to the planes and acts like an electric field applied to {\it one-dimensional} carriers in disordered semiconductors. As in flux arrays with columnar pins, there is a regime where the dynamics is dominated by superkink excitations that correspond to Mott variable range hopping (VRH) of carriers. In one dimension, however, rare events, such as large regions void of twin planes, can impede VRH and dominate transport in samples …

Ac Response Of The Flux-Line Liquid In High-Tc Superconductors, Lee-Wen Chen, M. Cristina Marchetti

Physics - All Scholarship

We use a hydrodynamics theory to discuss the response of a viscous flux-line liquid to an ac perturbation applied at the surface of the sample. The theory incorporates viscoelastic effects and describes the crossover between liquid-like and solid-like response of the vortex array as the frequency of the perturbation increases. A large viscosity from flux-line interactions and entanglement leads to viscous screening of surface fields. As a result, two frequency-dependent length scales are needed to describe the penetration of an ac field. For large viscosities the imaginary part of the ac permeability can exihibit, in addition to the well-know peak …