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Transformation of spin information into large electrical signals using carbon nanotubes

Abstract

Spin electronics (spintronics) exploits the magnetic nature of electrons, and this principle is commercially applied in, for example, the spin valves of disk-drive read heads. There is currently widespread interest in developing new types of spintronic devices based on industrially relevant semiconductors, in which a spin-polarized current flows through a lateral channel between a spin-polarized source and drain1,2. However, the transformation of spin information into large electrical signals is limited by spin relaxation, so that the magnetoresistive signals are below 1% (ref. 2). Here we report large magnetoresistance effects (61% at 5 K), which correspond to large output signals (65 mV), in devices where the non-magnetic channel is a multiwall carbon nanotube that spans a 1.5 μm gap between epitaxial electrodes of the highly spin polarized3,4 manganite La0.7Sr0.3MnO3. This spintronic system combines a number of favourable properties that enable this performance; the long spin lifetime in nanotubes due to the small spin–orbit coupling of carbon; the high Fermi velocity in nanotubes that limits the carrier dwell time; the high spin polarization in the manganite electrodes, which remains high right up to the manganite–nanotube interface; and the resistance of the interfacial barrier for spin injection. We support these conclusions regarding the interface using density functional theory calculations. The success of our experiments with such chemically and geometrically different materials should inspire new avenues in materials selection for future spintronics applications.

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Figure 1: LSMO–CNT–LSMO device.
Figure 2: First-principles calculations of device interfaces.
Figure 3: MR for a LSMO–CNT–LSMO device.
Figure 4: Temperature and bias dependence of peak MR.

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References

  1. Žutić, I., Fabian, J. & das Sarma, S. Spintronics: Fundamentals and applications. Rev. Mod. Phys. 76, 323–410 (2004)

    Article  ADS  Google Scholar 

  2. Jonker, B. T. & Flatté, M. E. F. in Nanomagnetism (eds Mills, D. L. & Bland, J. A. C.) 227–272 (Elsevier, Amsterdam, 2006)

    Google Scholar 

  3. Park, J.-H. et al. Direct evidence for a half-metallic ferromagnet. Nature 392, 794–796 (1998)

    Article  ADS  CAS  Google Scholar 

  4. Bowen, M. et al. Nearly total spin-polarization in La2/3Sr1/3MnO3 from tunnelling experiments. Appl. Phys. Lett. 82, 233–235 (2003)

    Article  ADS  CAS  Google Scholar 

  5. Datta, S. & Das, B. Electric analog of the electro-optic modulator. Appl. Phys. Lett. 56, 665–667 (1990)

    Article  ADS  CAS  Google Scholar 

  6. Dresselhaus, M. S., Dresselhaus, G. & Avouris, Ph (eds) Carbon Nanotubes (Springer, Berlin, 2001)

    Book  Google Scholar 

  7. Buitelaar, M. R., Bachtold, A., Nussbaumer, T., Iqbal, M. & Schönenberger, C. Multiwall carbon nanotubes as quantum dots. Phys. Rev. Lett. 88, 156801 (2002)

    Article  ADS  CAS  Google Scholar 

  8. Joachim, C., Gimzewski, J. K. & Aviram, A. Electronics using hybrid-molecular and mono-molecular devices. Nature 408, 541–548 (2000)

    Article  ADS  CAS  Google Scholar 

  9. Petta, J. R., Slater, S. K. & Ralph, D. C. Spin-dependent transport in molecular tunnel junctions. Phys. Rev. Lett. 93, 136601 (2004)

    Article  ADS  CAS  Google Scholar 

  10. Pasupathy, A. N. et al. The Kondo effect in the presence of ferromagnetism. Science 306, 86–89 (2004)

    Article  ADS  CAS  Google Scholar 

  11. Tsukagoshi, K., Alphenaar, B. W. & Ago, H. Coherent transport of electron spin in a ferromagnetically contacted carbon nanotube. Nature 401, 572–574 (1999)

    Article  ADS  CAS  Google Scholar 

  12. Sahoo, S. et al. Electric field control of spin transport. Nature Phys. 1, 99–102 (2005)

    Article  ADS  CAS  Google Scholar 

  13. Jensen, A., Hauptmann, J. R., Nygård, J. & Lindelof, P. E. Magnetoresistance in ferromagnetically contacted single-wall carbon nanotubes. Phys. Rev. B 72, 035419 (2005)

    Article  ADS  Google Scholar 

  14. Tombros, N., van der Molen, S. J. & van Wees, B. J. Separating spin and charge transport in single-wall carbon nanotubes. Phys. Rev. B 73, 233403 (2006)

    Article  ADS  Google Scholar 

  15. Meservey, R. & Tedrow, P. M. Spin-polarized electron tunneling. Phys. Rep. 238, 173–243 (1994)

    Article  ADS  Google Scholar 

  16. Jorgensen, H. I., Grove-Rasmussen, K., Novotny, T., Flensberg, K. & Lindelof, P. E. Electron transport in single-wall carbon nanotube weak links in the Fabry-Perot regime. Phys. Rev. Lett. 96, 207003 (2006)

    Article  ADS  CAS  Google Scholar 

  17. Mieville, L., Wordledge, D., Geballe, T. H., Contreras, R. & Char, K. Transport across conducting ferromagnetic oxides/metal interfaces. Appl. Phys. Lett. 73, 1736–1739 (1998)

    Article  ADS  CAS  Google Scholar 

  18. Hueso, L. E. et al. Electrical transport between epitaxial manganites and carbon nanotubes. Appl. Phys. Lett. 88, 083120 (2006)

    Article  ADS  Google Scholar 

  19. Kohn, W. & Sham, L. J. Self-consistent equations including exchange and correlations effects. Phys. Rev. 140, 1133–1138 (1965)

    Article  ADS  MathSciNet  Google Scholar 

  20. George, J. M. et al. Electrical spin injection in GaMnAs-based junctions. Mol. Phys. Rep. 40, 23–33 (2004)

    CAS  Google Scholar 

  21. Fert, A., George, J. M., Jaffrès, H. & Mattana, R. Semiconductors between spin-polarized source and drain. IEEE Trans. Electron. Devices (special issue on spintronics) (in the press); preprint at 〈http://arxiv.org/abs/cond-mat/0612495〉 (2006).

  22. Jedema, F. J., Heersche, H. B., Filip, A. T., Baselmans, J. J. A. & van Wees, B. J. Electrical detection of spin precession in a metallic mesoscopic spin valve. Nature 416, 713–716 (2002)

    Article  ADS  CAS  Google Scholar 

  23. Schmidt, G., Ferrand, D., Molenkamp, L. W., Filip, A. T. & van Wees, B. J. Fundamental obstacle for electrical spin injection from a ferromagnetic metal into a diffusive semiconductor. Phys. Rev. B 62, 4790–4793 (2000)

    Article  ADS  Google Scholar 

  24. Rashba, E. Theory of electrical spin injection: tunnel contacts as a solution of the conductivity mismatch problem. Phys. Rev. B 62, 16267–16270 (2000)

    Article  ADS  Google Scholar 

  25. Fert, A. & Jaffrès, H. Conditions for efficient spin injection from a ferromagnetic metal into a semiconductor. Phys. Rev. B 64, 184420 (2001)

    Article  ADS  Google Scholar 

  26. Smith, D. L. & Silver, R. N. Electrical spin injection into semiconductors. Phys. Rev. B 64, 045323 (2001)

    Article  ADS  Google Scholar 

  27. Mattana, R. et al. Electrical detection of spin accumulation in a p-type GaAs quantum well. Phys. Rev. Lett. 90, 166601 (2003)

    Article  ADS  CAS  Google Scholar 

  28. Bowen, M. et al. Spin-polarized tunnelling spectroscopy in tunnel junctions with half-metallic electrodes. Phys. Rev. Lett. 95, 137203 (2005)

    Article  ADS  CAS  Google Scholar 

  29. Soler, J. M. et al. The SIESTA method for ab initio order-N materials simulation. J. Phys. Condens. Matter 14, 2745–2779 (2002)

    Article  ADS  CAS  Google Scholar 

  30. Ferrari, V., Pruneda, J. M. A. & Artacho, E. Density functionals and half-metallicity in La2/3Sr1/3MnO3 . Phys. Stat. Sol. a 203, 1437–1441 (2006)

    Article  ADS  CAS  Google Scholar 

Download references

Acknowledgements

We thank G. A. J. Amaratunga, M. Bibes, H. Bouchiat, L. Brey, M. R. Buitelaar, M. J. Calderón, S. N. Cha, M. Chhowalla, A. Cottet, H. Jaffrès, D.-J. Kang, T. Kontos, P. Seneor and N. A. Spaldin. This work was funded by the UK EPSRC, NERC, BNFL, The Royal Society, the Spanish MEC (J.M.P.), Donostia International Physics Center (E.A.) and the EU.

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Correspondence to Neil D. Mathur.

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Hueso, L., Pruneda, J., Ferrari, V. et al. Transformation of spin information into large electrical signals using carbon nanotubes. Nature 445, 410–413 (2007). https://doi.org/10.1038/nature05507

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