Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.29: Poster

Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B

Phase diagram close to a conductance plateau transition in a quantum wire — •Matthias Sitte¹, Julia S. Meyer², Achim Rosch¹, and Markus Garst¹ — ¹Institut für Theoretische Physik, Universität zu Köln, 50937 Köln — ²Department of Physics, The Ohio State University, Ohio 43210, USA

We consider a quantum wire of spin-polarized (spinless) electrons close to the quantum phase transition where a second sub-band becomes activated as a function of gate voltage resulting in a jump of the zero temperature conductance. The filled first sub-band is treated as a Luttinger liquid, and it exchanges pairs of electrons with the second sub-band. It was shown in Ref. [1] that the conductance plateau transition is preempted by the formation of an inter-band pairing state. In the limit of infinitely strong inter-band density-density coupling, the latter transition is of Ising type. We perform a perturbative analysis around this strong coupling limit and determine the phase diagram. We find that the critical Ising mode induces superconducting fluctuations in the Luttinger liquid of the filled band, that are reflected in a logarithmically strong attractive interaction and a corresponding reduction of its plasmon velocity. We discuss possible consequences of this strong renormalization like a fluctuation-induced first order transition to a phase separated state preempting Ising criticality.

[1] J. S. Meyer, K. A. Matveev, and A. I. Larkin, Phys. Rev. Lett. 98, 126404 (2007).