Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 31: Low-dimensional Systems - Models I

TT 31.2: Vortrag

Donnerstag, 29. März 2007, 18:00–18:15, H19

Indirect forces between impurities in one-dimensional quantum liquids — •Peter Wächter, Volker Meden, and Kurt Schönhammer — Institut für Theoretische Physik, Universität Göttingen, Göttingen, Germany

We investigate the indirect interaction between two isolated impurities in a Luttinger liquid modeled by a microscopic lattice model. To treat the electron-electron interaction U the functional renormalization group method is used. For comparison we also study the U=0 case. For all U and generic values of the strength of the impurities we find that the impurity interaction as a function of their separation r oscillates between being attractive and repulsive. For U=0 the amplitude of the interaction energy decays as 1/r. For U>0 the decay for small separations is governed by a U dependent exponent larger than −1, which crosses over to −1 for large r. The crossover scale depends on the impurity strength and U. We briefly comment on the case of attractive interaction U<0 and the relation between the sign changes of the impurity interaction and transport resonances. In the special case of half-filling and for U ≥ 0 we find that by fine tuning the impurity parameters one can create a situation in which the impurity interaction becomes purely attractive.