Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 2: Quantum-Critical Phenomena

TT 2.2: Vortrag

Montag, 26. März 2007, 09:45–10:00, H19

Thermoelectric transport in the vicinity of a superconductor-metal quantum phase transition in nanowires — •Bernd Rosenow, Adrian Del Maestro, and Subir Sachdev — Department of Physics, Harvard University, Cambridge, MA 02138, USA

We consider the field theory for a zero temperature transition between superconducting and diffusive metallic states in very thin wires due to a cooper pair breaking mechanism, e.g. a magnetic field in the wire direction or disorder in an unconventional superconductor. The critical theory contains current reducing fluctuations in the guise of both quantum and thermally activated phase slips. In a large-N limit, we calculate the universal dependence of electrical and thermal conductivity on both pair breaking strength and temperature. We find that the conductivity has a non-monotonic temperature dependence on the metallic side of the transition and that the Wiedemann-Franz law is obeyed at low temperatures. In the quantum critical region, we study the dynamics of a two-component order paramter field via Monte Carlo simulation of a Langevin equation and compare with the large-N result.