Plasmon-induced carrier polarization in semiconductor nanocrystals



Spintronics1 and valleytronics2 are emerging quantum electronic technologies that rely on using electron spin and multiple extrema of the band structure (valleys), respectively, as additional degrees of freedom. There are also collective properties of electrons in semiconductor nanostructures that potentially could be exploited in multifunctional quantum devices. Specifically, plasmonic semiconductor nanocrystals3,4,5,6,7,8,9,10 offer an opportunity for interface-free coupling between a plasmon and an exciton. However, plasmon–exciton coupling in single-phase semiconductor nanocrystals remains challenging because confined plasmon oscillations are generally not resonant with excitonic transitions. Here, we demonstrate a robust electron polarization in degenerately doped In2O3 nanocrystals, enabled by non-resonant coupling of cyclotron magnetoplasmonic modes11 with the exciton at the Fermi level. Using magnetic circular dichroism spectroscopy, we show that intrinsic plasmon–exciton coupling allows for the indirect excitation of the magnetoplasmonic modes, and subsequent Zeeman splitting of the excitonic states. Splitting of the band states and selective carrier polarization can be manipulated further by spin–orbit coupling. Our results effectively open up the field of plasmontronics, which involves the phenomena that arise from intrinsic plasmon–exciton and plasmon–spin interactions. Furthermore, the dynamic control of carrier polarization is readily achieved at room temperature, which allows us to harness the magnetoplasmonic mode as a new degree of freedom in practical photonic, optoelectronic and quantum-information processing devices.

  • Subscribe to Nature Nanotechnology for full access:



Additional access options:

Already a subscriber?  Log in  now or  Register  for online access.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


  1. 1.

    Zutic, I., Fabian, J. & Das Sarma, S. Spintronics: fundamentals and applications. Rev. Mod. Phys. 76, 323–410 (2004).

  2. 2.

    Schaibley, J. R. et al. Valleytronics in 2D materials. Nat. Rev. Mater. 1, 16055 (2016).

  3. 3.

    Wang, T. & Radovanovic, P. V. Free electron concentration in colloidal indium tin oxide nanocrystals determined by their size and structure. J. Phys. Chem. C 115, 406–413 (2011).

  4. 4.

    Buonsanti, R., Llordes, A., Aloni, S., Helms, B. A. & Milliron, D. J. Tunable infrared absorption and visible transparency of colloidal aluminum-doped zinc oxide nanocrystals. Nano Lett. 11, 4706–4710 (2011).

  5. 5.

    Fang, H., Hegde, M., Yin, P. & Radovanovic, P. V. Tuning plasmon resonance of In2O3 nanocrystals throughout the mid-infrared region by competition between electron activation and trapping. Chem. Mater. 29, 4970–4979 (2017).

  6. 6.

    Gordon, T. R. et al. Shape-dependent plasmonic response and directed self-assembly in a new semiconductor building block, indium-doped cadmium oxide (ICO). Nano Lett. 13, 2857–2863 (2013).

  7. 7.

    Faucheaux, J. A. & Jain, P. K. Plasmons in photocharged ZnO nanocrystals revealing the nature of charge dynamics. J. Phys. Chem. Lett. 4, 3024–3030 (2013).

  8. 8.

    Schimpf, A. M., Thakkar, N., Gunthardt, C. E., Masiello, D. J. & Gamelin, D. R. Charge-tunable quantum plasmons in colloidal semiconductor nanocrystals. ACS Nano 8, 1065–1072 (2014).

  9. 9.

    Luther, J. M., Jain, P. K., Ewers, T. & Alivisatos, A. P. Localized surface plasmon resonances arising from free carriers in doped quantum dots. Nat. Mater. 10, 361–366 (2011).

  10. 10.

    Gordon, T. R. et al. Nonaqueous synthesis of TiO2 nanocrystals using TiF4 to engineer morphology, oxygen vacancy concentration, and photocatalytic activity. J. Am. Chem. Soc. 134, 6751–6761 (2012).

  11. 11.

    Pineider, F. et al. Circular magnetoplasmonic modes in gold nanoparticles. Nano Lett. 13, 4785–4789 (2013).

  12. 12.

    Maier, S. A. Plasmonics: Fundamentals and Applications (Springer, New York, 2007).

  13. 13.

    Atwater, H. A. & Polman, A. Plasmonics for improved photovoltaic devices. Nat. Mater. 9, 205–213 (2010).

  14. 14.

    Stewart, M. E. et al. Nanostructured plasmonic sensors. Chem. Rev. 108, 494–521 (2008).

  15. 15.

    Huang, X., Jain, P. K., El-Sayed, I. H. & El-Sayed, M. A. Plasmonic photothermal therapy (PPTT) using gold nanoparticles. Lasers Med. Sci. 23, 217–228 (2008).

  16. 16.

    Shim, M. & Guyot-Sionnest, P. n-type colloidal semiconductor nanocrystals. Nature 407, 981–983 (2000).

  17. 17.

    Comin, A. & Manna, L. New materials for tunable plasmonic colloidal nanocrystals. Chem. Soc. Rev. 43, 3957–3975 (2014).

  18. 18.

    Sachet, E. et al. Dysprosium-doped cadmium oxide as a gateway material for mid-infrared plasmonics. Nat. Mater. 14, 414–420 (2015).

  19. 19.

    Lee, J., Hernandez, P., Lee, J., Govorov, A. O. & Kotov, N. A. Exciton–plasmon interactions in molecular spring assemblies of nanowires and wavelength-based protein detection. Nat. Mater. 6, 291–295 (2007).

  20. 20.

    Zhang, J., Tang, Y., Lee, K. & Ouyang, M. Tailoring light–matter–spin interactions in colloidal hetero-nanostructures. Nature 466, 91–95 (2010).

  21. 21.

    Uchida, K. et al. Generation of spin currents by surface plasmon resonance. Nat. Commun. 6, 5910 (2015).

  22. 22.

    Schimpf, A. M., Lounis, S. D., Runnerstrom, E. L., Milliron, D. J. & Gamelin, D. R. Redox chemistries and plasmon energies of photodoped In2O3 and Sn-doped In2O3 (ITO) nanocrystals. J. Am. Chem. Soc. 137, 518–524 (2015).

  23. 23.

    Piepho, S. B. & Schatz, P. N. Group Theory in Spectroscopy with Applications to Magnetic Circular Dichroism (Wiley, New York, 1983).

  24. 24.

    Ding, D. et al. Non-stoichiometric MoO3–x quantum dots as a light-harvesting material for interfacial water evaporation. Chem. Commun. 53, 6744–6747 (2017).

  25. 25.

    Fedorov, A. V., Baranov, A. V. & Inoue, K. Exciton–phonon coupling in semiconductor quantum dots: resonant Raman scattering. Phys. Rev. B 56, 7491–7502 (1997).

  26. 26.

    Radović, M. et al. Infrared study of plasmon–phonon coupling in pure and Nd-doped CeO2−y nanocrystals. J. Phys. D 48, 065301 (2015).

  27. 27.

    Beye, M. et al. Dynamics of electron–phonon scattering: crystal- and angular-momentum transfer probed by resonant inelastic -ray scattering. Phys. Rev. Lett. 103, 237401 (2009).

  28. 28.

    Furdyna, J. K. Diluted magnetic semiconductors. J. Appl. Phys. 64, R29–R64 (1988).

  29. 29.

    Dietl, T. A ten-year perspective on dilute magnetic semiconductors and oxides. Nat. Mater. 9, 965–974 (2010).

  30. 30.

    Hegde, M., Farvid, S. S., Hosein, I. D. & Radovanovic, P. V. Tuning manganese dopant spin interactions in single GaN nanowires at room temperature. ACS Nano 5, 6365–6373 (2011).

  31. 31.

    Johns, R. W. et al. Direct observation of narrow mid-infrared plasmon linewidths of single metal oxide nanocrystals. Nat. Commun. 7, 11583 (2016).

  32. 32.

    Hutfluss, L. N. & Radovanovic, P. V. Controlling the mechanism of phase transformation of colloidal In2O3 nanocrystals. J. Am. Chem. Soc. 137, 1101–1108 (2015).

  33. 33.

    Wang, T. & Radovanovic, P. V. In-situ enhancement of the blue photoluminescence of colloidal Ga2O3 nanocrystals by promotion of defect formation in reducing conditions. Chem. Commun. 47, 7161–7163 (2011).

  34. 34.

    Dave, N., Pautler, B. G., Farvid, S. S. & Radovanovic, P. V. Synthesis and surface control of colloidal Cr3+-doped SnO2 transparent magnetic semiconductor nanocrystals. Nanotechnology 21, 134023 (2010).

  35. 35.

    Mason, W. R. A Practical Guide to Magnetic Circular Dichroism Spectroscopy (Wiley, Hoboken, 2007).

  36. 36.

    Ju, L. et al. Interplay between size, composition and phase transition of nanocrystalline Cr3+-doped BaTiO3 as a path to multiferroism in perovskite-type oxides. J. Am. Chem. Soc. 134, 1136–1146 (2012).

  37. 37.

    Farvid, S. S. et al. Evidence of charge-transfer ferromagnetism in transparent diluted magnetic oxide nanocrystals: switching the mechanism of magnetic interactions. J. Am. Chem. Soc. 136, 7669–7679 (2014).

Download references


We acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC) (RGPIN-2015-67304032), Canada Foundation for Innovation (Project no. 204782) and the University of Waterloo (UW-Bordeaux Collaborative Research Grant). This research was undertaken thanks, in part, to funding from the Canada First Research Excellence Fund. P.V.R. acknowledges the support from the Canada Research Chairs Program (NSERC).

Author information


  1. Department of Chemistry, University of Waterloo, Waterloo, ON, Canada

    • Penghui Yin
    • , Yi Tan
    • , Hanbing Fang
    • , Manu Hegde
    •  & Pavle V. Radovanovic


  1. Search for Penghui Yin in:

  2. Search for Yi Tan in:

  3. Search for Hanbing Fang in:

  4. Search for Manu Hegde in:

  5. Search for Pavle V. Radovanovic in:


P.Y. and P.V.R. designed the experiments. P.Y., Y.T. and H.F. prepared and characterized the samples. P.Y. and Y.T. conducted MCD measurements. P.Y. analysed the data. M.H. performed the DFT calculations and analysis. P.V.R. and P.Y. interpreted the results and wrote the manuscript with contributions from the other authors. P.V.R. conceived and supervised the project.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Pavle V. Radovanovic.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–9, Supplementary Text