Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 58: Poster Session Transport & Matter at Low Temperature
TT 58.1: Poster
Donnerstag, 14. März 2013, 15:00–19:00, Poster D
Weak localization and magnetoresistance in a two-leg ladder model — •Michael P. Schneider1,2, Sam T. Carr2, Igor V. Gornyi2, and Alexander D. Mirlin2 — 1Max-Born-Institut, 12489 Berlin, Germany — 2Institut für Theorie der Kondensierten Materie and DFG Center for Functional Nanostructures, Karlsruher Institut für Technologie, 76128 Karlsruhe, Germany
We analyze the weak-localization correction to the conductivity of a spinless two-leg ladder model in the limit of strong dephasing τφ≪ τtr, paying particular attention to the presence of a magnetic field, which leads to an unconventional magnetoresistance behavior. We find that the magnetic field leads to three different effects: (i) negative magnetoresistance due to the regular weak-localization correction, (ii) effective decoupling of the two chains, leading to positive magnetoresistance, and (iii) oscillations in the magnetoresistance originating from the nature of the low-energy collective excitations. All three effects can be observed depending on the parameter range, but it turns out that large magnetic fields always decouple the chains and thus lead to the curious effect of magnetic-field-enhanced localization [1].
[1] M. P. Schneider, S. T. Carr, I. V. Gornyi and A. D. Mirlin, Phys. Rev. B 86, 155141 (2012)