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HL: Fachverband Halbleiterphysik

HL 41: Organic semiconductors

HL 41.9: Vortrag

Donnerstag, 28. Februar 2008, 17:15–17:30, ER 270

Magnetoresistance effects in a PTCDI based ferromagnet/organic semiconductor hybrid structure — •Matthias Grünewald¹, Markus Michelfeit¹, Georg Schmidt¹, Rüdiger Schmidt², Frank Würthner², and Laurens W. Molenkamp¹ — ¹Experimentelle Physik 3, Universität Würzburg, Am Hubland, 97074 Würzburg — ²Organische Chemie 2, Universität Würzburg, Am Hubland, 97074 Würzburg

Organic semiconductors (OSC) are promising materials for spintronic devices because of their very long spin relaxation times. Already in 2004 a first OSC based spin valve has been demonstrated [Xiong et al, Nature 427, 2004]. Most of the experiments on OSC based spin valve like structures were carried out using low mobility OSC like Alq3. The low mobility, however, results in either low currents or high bias voltages, making the difference between true diffusive spin transport or tunnelling barely discernable. Here we present a spin valve structure based on LSMO (lanthanum strontium manganese oxide) and Co as electrode materials and a novel UHV deposited PTCDI based OSC. The Co contacts are deposited in-situ after OSC deposition. The device shows high field magnetoresistance (HFMR) at 4K superimposed by a spin valve like switching behaviour when a magnetic field is applied in plane of the sample. No magnetoresistance can be observed for fields perpendicular to the plane, excluding any influence of organic magnetoresistance (OMAR). The magnitude of the HFMR depends on the applied bias voltage with a maximum at about 1.5 V. This work is funded by the EU within the FP6 project OFSPIN.