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Long-lived photoinduced magnetization in copper-doped ZnSe–CdSe core–shell nanocrystals


Nanoscale materials have been investigated extensively for applications in memory and data storage. Recent advances include memories based on metal nanoparticles1, nanoscale phase-change materials2 and molecular switches3. Traditionally, magnetic storage materials make use of magnetic fields to address individual storage elements. However, new materials with magnetic properties addressable via alternative means (for example, electrical or optical) may lead to improved flexibility and storage density and are therefore very desirable. Here, we demonstrate that copper-doped chalcogenide nanocrystals exhibit not only the classic signatures of diluted magnetic semiconductors4—namely, a strong spin-exchange interaction between paramagnetic Cu2+ dopants and the conduction/valence bands of the host semiconductor—but also show a pronounced and long-lived photoinduced enhancement of their paramagnetic response. Magnetic circular dichroism studies reveal that paramagnetism in these nanocrystals can be controlled and increased by up to 100% when illuminated with above-gap (blue/ultraviolet) light. These materials retain a memory of the photomagnetization for hour-long timescales in the dark, with effects persisting up to 80 K.

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Figure 1: Cu-doped ZnSe–CdSe nanocrystals: a nanoscale diluted magnetic semiconductor exhibiting spd exchange.
Figure 2: Photo-induced enhancement of paramagnetization in Cu:ZnSe–CdSe nanocrystals.
Figure 3: Long-lived photoinduced magnetization in Cu-doped nanocrystals.
Figure 4: Influence of temperature, and a model of photoinduced paramagnetization.


  1. Zijlstra, P., Chon, J. W. M. & Gu, M. Five-dimensional optical recording mediated by surface plasmons in gold nanorods. Nature 459, 410–413 (2009).

    Article  CAS  Google Scholar 

  2. Wuttig, M. & Yamada, N. Phase-change materials for rewriteable data storage. Nature Mater. 6, 824–832 (2007).

    Article  CAS  Google Scholar 

  3. Green, J. E. et al. A 160-kilobit molecular electronic memory patterned at 1011 bits per square centimetre. Nature 445, 414–417 (2007).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  5. Pradhan, N., Goorskey, D., Thessing, J. & Peng, X. G. An alternative of CdSe nanocrystal emitters: pure and tunable impurity emissions in ZnSe nanocrystals. J. Am. Chem. Soc. 127, 17586–17587 (2005).

    Article  CAS  Google Scholar 

  6. Srivastava, B. B., Jana, S. & Pradhan, N. Doping Cu in semiconductor nanocrystals: some old and some new physical insights. J. Am. Chem. Soc. 133, 1007–1015 (2011).

    Article  CAS  Google Scholar 

  7. Viswanatha, R., Brovelli, S., Pandey, A., Crooker, S. A. & Klimov, V. I. Copper-doped inverted core/shell nanocrystals with ‘permanent’ optically active holes. Nano Lett. 11, 4753–4758 (2011).

    Article  CAS  Google Scholar 

  8. Brovelli, S., Galland, C., Viswanatha, R. & Klimov, V. I. Tuning radiative recombination in Cu-doped nanocrystals via electrochemical control of surface trapping. Nano Lett. 12, 4372–4379 (2012).

    Article  CAS  Google Scholar 

  9. Bhaumik, S., Ghosh, B. & Pal, A. J. Color tunable light-emitting diodes based on copper doped semiconducting nanocrystals. Appl. Phys. Lett. 99, 083106 (2011).

    Article  Google Scholar 

  10. Stringfellow, G. B. & Bube, R. H. Photoelectronic properties of ZnSe crystals. Phys. Rev. 171, 903–915 (1968).

    Article  CAS  Google Scholar 

  11. Peka, P. & Schulz, H-J. Empirical one-electron model of optical transitions in Cu-doped ZnS and CdS. Physica B 193, 57–65 (1994).

    Article  CAS  Google Scholar 

  12. Godlewski, M., Lamb, W. E. & Cavenett, B. C. ODMR investigations of IR photoluminescence in ZnS:Cu. J. Phys. C 15, 3925–3942 (1982).

    Article  CAS  Google Scholar 

  13. Godlewski, M., Lamb, W. E. & Cavenett, B. C. ODMR investigations of recombination processes in ZnSe:Cu. Solid State Commun. 39, 595–599 (1981).

    Article  CAS  Google Scholar 

  14. Kacman, P. Spin interactions in diluted magnetic semiconductors and magnetic semiconductor structures. Semicond. Sci. Technol. 16, R25–R39 (2001).

    Article  CAS  Google Scholar 

  15. Schulz, H-J. Optical properties of 3d transition metals in IIVI compounds. J. Cryst. Growth 59, 65–80 (1982).

    Article  CAS  Google Scholar 

  16. Kreissl, J. & Schulz, H-J. Transition-metal impurities in IIVI semiconductors: characterization and switching of charge states. J. Cryst. Growth 161, 239–249 (1996).

    Article  CAS  Google Scholar 

  17. Blinowski, J. & Kacman, P. Kinetic exchange in diluted magnetic semiconductors. Phys. Rev. B 46, 12298–12304 (1992).

    Article  CAS  Google Scholar 

  18. Bhattacharjee, A. K. Interaction between band electrons and transition-metal ions in diluted magnetic semiconductors. Phys. Rev. B 46, 5266–5273 (1992).

    Article  CAS  Google Scholar 

  19. Bhattacharjee, A. K. Orbital exchange in diluted magnetic semiconductors. J. Cryst. Growth 138, 895–899 (1994).

    Article  CAS  Google Scholar 

  20. Mizokawa, T. & Fujimori, A. pd exchange interaction for 3d transition-metal impurities in II–VI semiconductors. Phys. Rev. B 56, 6669–6672 (1997).

    Article  CAS  Google Scholar 

  21. Herng, T. S. et al. Room-temperature ferromagnetism of Cu-doped ZnO films probed by soft X-ray magnetic circular dichroism. Phys. Rev. Lett. 105, 207201 (2010).

    Article  CAS  Google Scholar 

  22. Norris, D. J., Yao, N., Charnock, F. T. & Kennedy, T. A. High-quality manganese-doped ZnSe nanocrystals. Nano Lett. 1, 3–7 (2001).

    Article  CAS  Google Scholar 

  23. Archer, P. I., Santangelo, S. A. & Gamelin, D. R. Direct observation of spd exchange interactions in colloidal Mn2+- and Co2+-doped CdSe quantum dots. Nano Lett. 7, 1037–1043 (2007).

    Article  CAS  Google Scholar 

  24. Bussian, D. A. et al. Tunable magnetic exchange interactions in manganese-doped inverted core–shell ZnSe–CdSe nanocrystals. Nature Mater. 8, 35–40 (2009).

    Article  CAS  Google Scholar 

  25. De Wit, M. Zeeman effect in absorption spectrum of copper-doped zinc sulfide. Phys. Rev. 177, 441–447 (1969).

    Article  CAS  Google Scholar 

  26. Telahun, T. et al. Nonlinear Zeeman behavior of Cu2+ centers in ZnS and CdS explained by a Jahn–Teller effect. Phys. Rev. B 53, 1274–1286 (1996).

    Article  CAS  Google Scholar 

  27. Clerjaud, B. & Gelineau, A. Strong spin-lattice coupling of Kramers doublets. Phys. Rev. B 16, 82–85 (1977).

    Article  CAS  Google Scholar 

  28. Roussos, G., Nagel, J. & Schulz, H-J. Luminescent Ni+ centres and changes of the charge state of nickel ions in ZnS and ZnSe. Z. Phys. B 53, 95–107 (1983).

    Article  CAS  Google Scholar 

  29. Broser, I. & Schulz, H-J. A comparative study of infrared luminescence and some other optical and electrical properties of ZnS:Cu single crystals. J. Electrochem. Soc. 108, 545548 (1961).

    Article  Google Scholar 

  30. Dahan, P. & Fleurov, V. Possibility of a metastable state for a transition-metal impurity in semiconductor. Phys. Rev. B 53, 12845–12854 (1996).

    Article  CAS  Google Scholar 

  31. Ochsenbein, S. T. et al. Charge-controlled magnetism in colloidal doped semiconductor nanocrystals. Nature Nanotech. 4, 681–687 (2009).

    Article  CAS  Google Scholar 

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R.V., L.L., J.M.P., V.I.K. and S.A.C. are supported by the Chemical Sciences, Biosciences and Geosciences Division of the Office of Basic Energy Sciences, Office of Science, US Department of Energy. A.P. and S.B. acknowledge support from the Los Alamos LDRD programme.

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V.I.K., A.P., S.A.C. and S.B. conceived the study. A.P., R.V., L.L. and J.M.P. developed and synthesized the samples. A.P., S.B. and S.A.C. performed the measurements. A.P., S.B., V.I.K. and S.A.C. analysed the data and wrote the paper in consultation with all authors.

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Correspondence to V. I. Klimov or S. A. Crooker.

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Pandey, A., Brovelli, S., Viswanatha, R. et al. Long-lived photoinduced magnetization in copper-doped ZnSe–CdSe core–shell nanocrystals. Nature Nanotech 7, 792–797 (2012).

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