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Observation of extremely long spin relaxation times in an organic nanowire spin valve

Nature Nanotechnology volume 2, pages 216–219 (2007)Cite this article

Abstract

Organic semiconductors that are π-conjugated are emerging as an important platform for ‘spintronics’, which purports to harness the spin degree of freedom of a charge carrier to store, process and/or communicate information1. Here, we report the study of an organic nanowire spin valve device, 50 nm in diameter, consisting of a trilayer of ferromagnetic cobalt, an organic, Alq3, and ferromagnetic nickel. The measured spin relaxation time in the organic is found to be exceptionally long—between a few milliseconds and a second—and it is relatively temperature independent up to 100 K. Our experimental observations strongly suggest that the primary spin relaxation mechanism in the organic is the Elliott–Yafet mode, in which the spin relaxes whenever a carrier scatters and its velocity changes.

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Figure 1: Schematic representation of a nanowire spin valve structure.
Figure 2: Magnetoresistance traces at different temperatures.
Figure 3: TEM images of typical nanowire spin valve structures.
Figure 4: Temperature dependence of the spin relaxation length and time.

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Acknowledgements

This work is supported by the US Air Force Office of Scientific Research under grant FA9550-04-1-0261, by the National Science Foundation under grant ECS-0608854 and by the US Department of Energy under grant DE-AC02-98CH10886 (subcontract from Brookhaven National Laboratory).

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Authors and Affiliations

  1. Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, 23284, Virginia, USA

    S. Pramanik, C.-G. Stefanita, S. Patibandla & S. Bandyopadhyay

  2. Department of Electrical and Computer Engineering, University of Cincinnati, Cincinnati, 45221, Ohio, USA

    K. Garre, N. Harth & M. Cahay

Authors
  1. S. Pramanik
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  2. C.-G. Stefanita
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  5. K. Garre
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  7. M. Cahay
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Contributions

S.B., S.Pr. and M.C. conceived and designed the experiments, S.Pr., C.G.S. and S.Pa conducted the experiments, S.Pr and K.G. fabricated the structures and S.B. wrote the paper.

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Correspondence to S. Bandyopadhyay.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary figures S1 and S2 (PDF 435 kb)

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Pramanik, S., Stefanita, CG., Patibandla, S. et al. Observation of extremely long spin relaxation times in an organic nanowire spin valve. Nature Nanotech 2, 216–219 (2007). https://doi.org/10.1038/nnano.2007.64

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