Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

How to make a bilayer exciton condensate flow

Abstract

Among the many examples of Bose condensation considered in physics, electron–hole-pair (exciton) condensation has maintained special interest because of controversy about condensate properties. Although ideal condensates can support an exciton supercurrent, it has not been clear how such a current could be induced or detected. This paper addresses the electrical generation of exciton supercurrents in bilayer condensates (systems in which the electrons and holes are in separate layers) and reaches a surprising conclusion. We find that steady-state dissipationless currents cannot be induced simply by connecting the two layers in series to guarantee opposite currents in electron and hole layers, as has long been supposed. Instead, current should be injected into and removed from the same layer, and a conducting channel supplied to close the counterflow portion of supercurrent in the other layer.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Schematic illustration of a separately contacted bilayer exciton condensate.
Figure 2: Series-counterflow (S-CF) and drag-counterflow (D-CF) geometries.
Figure 3: One-dimensional toy-model self-consistent current distributions.

References

  1. Spielman, I. B., Eisenstein, J. P., Pfeiffer, L. N. & West, K. W. Resonantly enhanced tunneling in a double layer quantum Hall ferromagnet. Phys. Rev. Lett. 84, 5808–5811 (2000).

    Article  ADS  Google Scholar 

  2. Spielman, I. B., Eisenstein, J. P., Pfeiffer, L. N. & West, K. W. Observation of a linearly dispersing collective mode in a quantum Hall ferromagnet. Phys. Rev. Lett. 87, 036803 (2001).

    Article  ADS  Google Scholar 

  3. Tiemann, L. et al. Exciton condensate at a total filling factor of one in Corbino two-dimensional electron bilayers. Phys. Rev. B 77, 033306 (2008).

    Article  ADS  Google Scholar 

  4. Tiemann, L. et al. Critical tunneling currents in the regime of bilayerexcitons. New J. Phys. 10, 045018 (2008).

    Article  ADS  Google Scholar 

  5. Wiersma, R. D. et al. Activated transport in the separate layers that form the νT=1 exciton. Phys. Rev. Lett. 93, 266805 (2004).

    Article  ADS  Google Scholar 

  6. Tutuc, E., Shayegan, M. & Huse, D. A. Counterflow measurements in strongly correlated GaAs hole bilayers: Evidence for electron–hole pairing. Phys. Rev. Lett. 93, 036802 (2004).

    Article  ADS  Google Scholar 

  7. Blatt, J. M., Böer, K. W. & Brandt, W. Bose–Einstein condensation of excitons. Phys. Rev. 126, 1691–1692 (1962).

    Article  ADS  Google Scholar 

  8. Moon, K. et al. Spontaneous inter-layer coherence in double-layer quantum Hall systems: Charged vortices and Kosterlitz–Thouless phase transitions. Phys. Rev. B 51, 5138–5170 (1995).

    Article  ADS  Google Scholar 

  9. Fil, D. V. & Shevchenko, S. I. Interlayer tunneling and the problem of superfluidity in bilayer quantum Hall systems. Low Temp. Phys. 33, 780–782 (2007).

    Article  ADS  Google Scholar 

  10. Kogan, V. G. & Tavger, B. A. in Physics of p–n Junction and Semiconductor Devices (eds Ryvkin, S. M. & Shmartsev, Yu. V.) 39–45 (Plenum, New York, 1971).

    Book  Google Scholar 

  11. Khomeriki, R., Tkeshelashvili, L., Buishvili, T. & Revishvili, Sh. Directed transport in quantum Hall bilayers. Eur. Phys. J. B 51, 421–424 (2006).

    Article  ADS  Google Scholar 

  12. Min, H., Bistrizer, R., Su, J.-J. & MacDonald, A. H. Room-temperature superfluidity in graphene bilayers? PRB Rapid Commun. 78 (in the press); preprint at <http://arxiv.org/abs/0802.3462> (2008).

  13. Seamons, J. A., Tibbetts, D. R., Reno, J. L. & Lilly, M. P. Undoped electron–hole bilayers in a GaAsAlGaAs double quantum well. Appl. Phys. Lett. 90, 052103 (2007).

    Article  ADS  Google Scholar 

  14. Gupta, K. Das et al. Selective breakdown of Quantum Hall edge states and non-monotonic coulomb drag in a GaAs–AlGaAs electron–hole bilayer. Physica E 40, 1693–1696 (2008).

    Article  ADS  Google Scholar 

  15. Geim, A. K. & MacDonald, A. H. Graphene: Exploring carbon flatland. Phys. Today 60, 35–41 (2007).

    Google Scholar 

  16. Keldysh, L. V. & Kozlov, A. N. Collective properties of excitons in semiconductors. Sov. Phys.—JETP 27, 521–528 (1968).

    ADS  Google Scholar 

  17. Conti, S., Vignale, G. & MacDonald, A. H. Engineering superfluidity in electron–hole double layers. Phys. Rev. B 57, R6846–R6849 (1998).

    Article  ADS  Google Scholar 

  18. Fertig, H. A. Energy spectrum of a layered system in a strong magnetic field. Phys. Rev. B 40, 1087–1095 (1989).

    Article  ADS  Google Scholar 

  19. Rossi, E., Nunez, A. S. & MacDonald, A. H. Inter-layer transport in bilayer quantum Hall systems. Phys. Rev. Lett. 95, 266804 (2005).

    Article  ADS  Google Scholar 

  20. Eisenstein, J. P. & MacDonald, A. H. Bose–Einstein condensation of excitons in bilayer electron systems. Nature 432, 691–694 (2004).

    Article  ADS  Google Scholar 

  21. Eisenstein, J. P., Pfeiffer, L. N. & West, K. W. Independently contacted 2-dimensional electron systems in double quantum-wells. Appl. Phys. Lett. 57, 2324–2326 (1990).

    Article  ADS  Google Scholar 

  22. Datta, S. Electronic Transport in Mesoscopic Systems (Cambridge Univ. Press, Cambridge, 1995).

    Book  Google Scholar 

  23. Kohn, W. & Sherrington, D. Two kinds of bosons and bose condensates. Rev. Mod. Phys. 42, 1–11 (1970).

    Article  ADS  Google Scholar 

  24. Zhang, C.-H. & Joglekar, Y. N. Excitonic condensation of massless fermions in graphene bilayers. Phys. Rev. B 77, 233405 (2008).

    Article  ADS  Google Scholar 

  25. Lozovik, Yu. E. & Yudson, V. I. Feasibility of superfluidity of paired spatially separated electrons and holes; a new superconductivity mechanism. JETP Lett. 22, 274–276 (1975).

    ADS  Google Scholar 

Download references

Acknowledgements

This work has been supported by the Welch Foundation and by the National Science Foundation under grant DMR-0606489 and by SWAN-NRI. A.H.M. acknowledges long-standing interactions with J. Eisenstein, W. Dietsche and K. von Klitzing, which have informed this analysis, and discussions with M. Lilly, L. Tiemann and I. Spielman.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Jung-Jung Su.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Su, JJ., MacDonald, A. How to make a bilayer exciton condensate flow. Nature Phys 4, 799–802 (2008). https://doi.org/10.1038/nphys1055

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nphys1055

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing