Letter | Published:

Potential for spin-based information processing in a thin-film molecular semiconductor

Nature volume 503, pages 504508 (28 November 2013) | Download Citation

Abstract

Organic semiconductors are studied intensively for applications in electronics and optics1, and even spin-based information technology, or spintronics2. Fundamental quantities in spintronics are the population relaxation time (T1) and the phase memory time (T2): T1 measures the lifetime of a classical bit, in this case embodied by a spin oriented either parallel or antiparallel to an external magnetic field, and T2 measures the corresponding lifetime of a quantum bit, encoded in the phase of the quantum state. Here we establish that these times are surprisingly long for a common, low-cost and chemically modifiable organic semiconductor, the blue pigment copper phthalocyanine3, in easily processed thin-film form of the type used for device fabrication. At 5 K, a temperature reachable using inexpensive closed-cycle refrigerators, T1 and T2 are respectively 59 ms and 2.6 μs, and at 80 K, which is just above the boiling point of liquid nitrogen, they are respectively 10 μs and 1 μs, demonstrating that the performance of thin-film copper phthalocyanine is superior to that of single-molecule magnets over the same temperature range4. T2 is more than two orders of magnitude greater than the duration of the spin manipulation pulses, which suggests that copper phthalocyanine holds promise for quantum information processing, and the long T1 indicates possibilities for medium-term storage of classical bits in all-organic devices on plastic substrates.

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Acknowledgements

S.H. and Z.W. thank EPSRC (EP/F039948/1) for the award of a First Grant. S.H. and S.D. thank Kurt J. Lesker and EPSRC for a CASE award. Work at UCL and Imperial College was supported by the EPSRC Basic Technologies grant Molecular Spintronics (EP/F041349/1 and EP/F04139X/1). G.W.M. is supported by the Royal Society. I.S.T. thanks IARPA, NSERC (grant CNXP 22R81695) and PITP for support.

Author information

Author notes

    • Marc Warner
    • , Gavin W. Morley
    •  & Jules A. Gardener

    Present addresses: Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA (M.W.); Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK (G.W.M.); RMD Inc., 44 Hunt Street, Watertown, Massachusetts 02472, USA (J.A.G.).

    • A. Marshall Stoneham

    Deceased.

Affiliations

  1. London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1H 0AH, UK

    • Marc Warner
    • , Gavin W. Morley
    • , A. Marshall Stoneham
    • , Jules A. Gardener
    • , Andrew J. Fisher
    •  & Gabriel Aeppli
  2. London Centre for Nanotechnology and Department of Materials, Imperial College London, London SW7 2AZ, UK

    • Salahud Din
    • , Zhenlin Wu
    •  & Sandrine Heutz
  3. Pacific Institute of Theoretical Physics, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada

    • Igor S. Tupitsyn
  4. Institute of Structural & Molecular Biology and London Centre for Nanotechnology, University College London, London WC1E 6BT, UK

    • Christopher W. M. Kay

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Contributions

M.W. conducted the electron spin resonance measurements with input and supervision from G.A. and C.W.M.K. S.D., J.A.G. and Z.W. made and characterized the samples with input and supervision from S.H.. M.W., G.W.M., A.M.S., A.J.F., C.W.M.K. and G.A. analysed data, I.S.T. performed theoretical work, and M.W. wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Marc Warner or Gabriel Aeppli.

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DOI

https://doi.org/10.1038/nature12597

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