Magnetoresistance in pi-conjugated organic sandwich devices with varying hyperfine and spin-orbit coupling strengths, and varying dopant concentrations

Tho Duc Nguyen; Yugang Sheng; James Rybicki; Govindarajan Veeraraghavan; Markus Wohlgenannt

doi:10.1039/b617541d

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Magnetoresistance in pi-conjugated organic sandwich devices with varying hyperfine and spin-orbit coupling strengths, and varying dopant concentrations

Journal article

Peer reviewed

Magnetoresistance in pi-conjugated organic sandwich devices with varying hyperfine and spin-orbit coupling strengths, and varying dopant concentrations

Tho Duc Nguyen, Yugang Sheng, James Rybicki, Govindarajan Veeraraghavan and Markus Wohlgenannt

Journal of materials chemistry, Vol.17(19), pp.1995-2001

01/01/2007

DOI: 10.1039/b617541d

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Abstract

We study a recently discovered organic magnetoresistive (OMAR) effect whose underlying mechanism is currently not known with certainty. We examine the hypothesis that OMAR is caused by spin-dynamics by varying the strength of the hyperfine and spin-orbit coupling in the organic semiconductor material. We show that unlike most other materials, C-60 devices do not exhibit the OMAR effect. Therefore hydrogen atoms and the resulting strong nuclear hyperfine coupling is a necessary prerequisite for the observation of OMAR. We investigate the dependence of OMAR on the strength of the spin-coupling introduced by heavy atoms in two widely used organic semiconductors, and find the characteristic magnetic field scale shifts to much larger fields. We also study OMAR sandwich devices made from the conducting polymer PEDOT. We show that in PEDOT the observed effect is caused by interface resistance, distinct from the case of intrinsic devices where OMAR is related to the bulk resistance of the (undoped) organic semiconductor.

Chemistry

Chemistry, Physical

Materials Science

Materials Science, Multidisciplinary

Physical Sciences

Science & Technology

Technology

Details

Title: Subtitle: Magnetoresistance in pi-conjugated organic sandwich devices with varying hyperfine and spin-orbit coupling strengths, and varying dopant concentrations
Creators: Tho Duc Nguyen - University of Iowa
Yugang Sheng - University of Iowa
James Rybicki - University of Iowa
Govindarajan Veeraraghavan - University of Iowa
Markus Wohlgenannt - University of Iowa
Resource Type: Journal article
Publication Details: Journal of materials chemistry, Vol.17(19), pp.1995-2001
Publisher: Royal Soc Chemistry
DOI: 10.1039/b617541d
ISSN: 0959-9428
eISSN: 1364-5501
Number of pages: 7
Language: English
Date published: 01/01/2007
Academic Unit: Physics and Astronomy
Record Identifier: 9984428810002771

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