A new twist on organic spintronics; controlling transport in organic sandwich devices using fringe fields from ferromagnetic films

Markus Wohlgenannt, Michael E. Flatté, Nicholas J. Harmon, Fujian Wang, Andrew D. Kent, Ferran Macià, Peter Fischer, Mi Young Im

    Research output: Chapter in Book/Report/Conference proceedingConference contribution


    Random, spatially uncorrelated nuclear-hyperfine fields in organic materials dramatically affect electronic transport properties such as electrical conductivity, photoconductivity, and electroluminescence. Competition between spin-dynamics due to these spatially uncorrelated fields and an applied magnetic field leads to large magnetoresistance, even at room temperature where the thermodynamic influences of the resulting nuclear and electronic Zeeman splittings are negligible. Here, we discuss a new method of controlling the electrical conductivity of an organic film at room temperature, using the spatially varying magnetic fringe fields of a magnetically unsaturated ferromagnet. Fringe-field magnetoresistance has a magnitude of several percent, and is hysteretic and anisotropic. This new method of control is sensitive to even remanent magnetic states, leading to different conductivity values in the absence of an applied field. The fringe field effects are insensitive to the ferromagnetic film's thickness (and therefore the fringe field magnitude) but sensitive to the magnetic domain's correlation length. This points at fringe-field gradients as an important ingredient of this mechanism. We develop a model based on fringe-field induced polaron-pair spin-dynamics that successfully describes several key features of the experimental fringe-field magnetoresistance.

    Original languageEnglish (US)
    Title of host publicationSpintronics VI
    StatePublished - 2013
    Event6th Spintronics Symposium - San Diego, CA, United States
    Duration: Aug 25 2013Aug 29 2013

    Publication series

    NameProceedings of SPIE - The International Society for Optical Engineering
    ISSN (Print)0277-786X
    ISSN (Electronic)1996-756X


    Other6th Spintronics Symposium
    Country/TerritoryUnited States
    CitySan Diego, CA


    • fringe-field magnetoresistance
    • organic magnetoresistance
    • room-temperature magnetoresistance

    ASJC Scopus subject areas

    • Electronic, Optical and Magnetic Materials
    • Condensed Matter Physics
    • Computer Science Applications
    • Applied Mathematics
    • Electrical and Electronic Engineering


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