Bipolaron mechanism for organic magnetoresistance

P.A. Bobbert, T.D. Nguyen, F.W.A. Oost, van, B. Koopmans, M. Wohlgenannt

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404 Citations (Scopus)
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Abstract

We present a mechanism for the recently discovered magnetoresistance in disordered ?-conjugated materials, based on hopping of polarons and bipolaron formation, in the presence of the random hyperfine fields of the hydrogen nuclei and an external magnetic field. Within a simple model we describe the magnetic field dependence of the bipolaron density. MonteCarlo simulations including on-site and longer-range Coulomb repulsion show how this leads to positive and negative magnetoresistance. Depending on the branching ratio between bipolaron formation or dissociation and hopping rates, two different line shapes in excellent agreement with experiment are obtained.
Original languageEnglish
Article number216801
Pages (from-to)216801-1/4
Number of pages4
JournalPhysical Review Letters
Volume99
Issue number21
DOIs
Publication statusPublished - 2007

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