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Proceedings Paper

A new twist on organic spintronics: controlling transport in organic sandwich devices using fringe fields from ferromagnetic films
Author(s): Markus Wohlgenannt; Michael E. Flatté; Nicholas J. Harmon; Fujian Wang; Andrew D. Kent; Ferran Macià; Peter Fischer; Mi-Young Im
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Paper Abstract

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.

Paper Details

Date Published: 26 September 2013
PDF: 10 pages
Proc. SPIE 8813, Spintronics VI, 88130O (26 September 2013); doi: 10.1117/12.2024602
Show Author Affiliations
Markus Wohlgenannt, The Univ. of Iowa (United States)
Michael E. Flatté, The Univ. of Iowa (United States)
Nicholas J. Harmon, The Univ. of Iowa (United States)
Fujian Wang, The Univ. of Iowa (United States)
Andrew D. Kent, New York Univ. (United States)
Ferran Macià, New York Univ. (United States)
Peter Fischer, Lawrence Berkeley National Lab. (United States)
Mi-Young Im, Lawrence Berkeley National Lab. (United States)

Published in SPIE Proceedings Vol. 8813:
Spintronics VI
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi, Editor(s)

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