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.

  • Article
  • Published:

Donor impurity band exchange in dilute ferromagnetic oxides

Nature Materials volume 4, pages 173–179 (2005)Cite this article

Abstract

Dilute ferromagnetic oxides having Curie temperatures far in excess of 300 K and exceptionally large ordered moments per transition-metal cation challenge our understanding of magnetism in solids. These materials are high-k dielectrics with degenerate or thermally activated n-type semiconductivity. Conventional super-exchange or double-exchange interactions cannot produce long-range magnetic order at concentrations of magnetic cations of a few percent. We propose that ferromagnetic exchange here, and in dilute ferromagnetic nitrides, is mediated by shallow donor electrons that form bound magnetic polarons, which overlap to create a spin-split impurity band. The Curie temperature in the mean-field approximation varies as (xδ)1/2 where x and δ are the concentrations of magnetic cations and donors, respectively. High Curie temperatures arise only when empty minority-spin or majority-spin d states lie at the Fermi level in the impurity band. The magnetic phase diagram includes regions of semiconducting and metallic ferromagnetism, cluster paramagnetism, spin glass and canted antiferromagnetism.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Plots of magnetic moment per transition-metal cation in doped oxide thin films.
Figure 2: Representation of magnetic polarons.
Figure 3: The magnetic phase diagram for dilute ferromagnetic semiconductors.
Figure 4: Schematic band structure of an oxide with 3d impurities and a spin-split donor impurity band.
Figure 5: The magnetic moment of thin films produced from (Zn0.95M0.05)O targets by pulsed-laser deposition, for M = Sc – Cu, measured at room-temperature.
Figure 6: Magnetic moments measured on thin films of doped ZnO or SnO2 expressed in Bohr magnetons per unit substrate area.

Similar content being viewed by others

References

  1. Prellier, W., Fouchet, A. & Mercey, B. Oxide-diluted magnetic semiconductors: a review of the experimental status. J. Phys. Condens. Matter 15, R1583–R1601 (2003).

    Article  CAS  Google Scholar 

  2. Pearton, S. J. et al. Wide band gap ferromagnetic semiconductors and oxides J. Appl. Phys. 93, 1–13 (2003).

    Article  CAS  Google Scholar 

  3. Dietl, T. et al. Zener model description of ferromagnetism in zinc-blende magnetic semiconductors. Science 287, 1019–1022 (2000).

    Article  CAS  Google Scholar 

  4. Matsumoto, Y. et al. Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide Science 291, 854–856 (2001).

    Article  CAS  Google Scholar 

  5. Ueda, K., Tabata, H. & Kawai, T. Magnetic and electric properties of transition-metal-doped ZnO films. Appl. Phys. Lett. 79, 988–990 (2001).

    Article  CAS  Google Scholar 

  6. Ogale, S. B. et al. High temperature ferromagnetism with a giant magnetic moment in transparent Co-doped SnO2-δ . Phys. Rev. Lett. 91, 077205 (2003).

    Article  CAS  Google Scholar 

  7. Kim, J. Y. et al. Ferromagnetism induced by clustered Co in Co-doped anatase TiO2 thin films Phys. Rev. Lett. 90, 017401 (2003).

    Article  Google Scholar 

  8. Punnoose, A., Seehra, M. S., Park, W. K. & Moodera, J. S. On the room temperature ferromagnetism in Co-doped TiO2 films. J. Appl. Phys. 93, 7867–7869 (2003).

    Article  CAS  Google Scholar 

  9. Rode, K. et al. Magnetic semiconductors based on cobalt substituted ZnO. J. Appl. Phys. 93, 7676–7678 (2003).

    Article  CAS  Google Scholar 

  10. Ramachandran, S., Tiwari, A. & Narayan, J. Zn0.9Co0.1O-based diluted magnetic semiconducting thin films. Appl. Phys. Lett. 84, 5255–5257 (2004).

    Article  CAS  Google Scholar 

  11. Goodenough, J. B. Magnetism and the Chemical Bond (Interscience, New York, 1963).

    Google Scholar 

  12. Holtzberg, F., von Molnar, S. & Coey, J. M. D. Handbook on Semiconductors Vol. 3 (ed. Keller, S.) 850 (North Holland, Amsterdam, 1980).

    Google Scholar 

  13. Dietl, T. Ferromagnetic semiconductors. Semicond. Sci. Technol. 17, 377–392 (2002).

    Article  CAS  Google Scholar 

  14. Mott, N. F. Conduction in Noncrystalline Materials (Oxford Univ. Press, Oxford, 1987).

    Google Scholar 

  15. von Molnar, S. & Kasuya, T. in Proceedings of 10th International Conference on Physics of Semiconductors (eds Keller, S. P., Hensel, J. C. & Stern, F.) 233 (U.S.A.E.C. Division of Technical Information, Springfield, Vancouver, 1970).

    Google Scholar 

  16. Dietl, T. & Spalek, J. J. Effect of thermodynamic fluctuations of magnetization on the bound magnetic polaron in dilute magnetic semiconductors. Phys. Rev. B 28, 1548–1563 (1983).

    Article  CAS  Google Scholar 

  17. Wolff, P. A. Semiconductors and Semimetals Vol. 25 (eds Furdyna, J. R. & Kossut, J.) (Academic, San Diego 1988).

    Google Scholar 

  18. Angelescu, D. E. & Bhatt, R. N. Effective interaction Hamiltonian of polaron pairs in diluted magnetic semiconductors. Phys. Rev. B 65, 075211 (2002).

    Article  Google Scholar 

  19. Durst, A. C., Bhatt, R. N. & Wolff, P. A. Bound magnetic polaron interactions in insulating doped diluted magnetic semiconductors. Phys. Rev. B 65, 235205 (2002).

    Article  Google Scholar 

  20. Zallen, R. M. Physics of Amorphous Solids (Wiley, New York, 1983).

    Book  Google Scholar 

  21. Kaminski, A. & Das Sarma, S. Polaron percolation in diluted magnetic semiconductors. Phys. Rev. Lett. 88, 247202 (2002).

    Article  CAS  Google Scholar 

  22. Kasuya, T. Mobility of antiferromagnetic large polaron. Solid State Commun. 8, 1635 (1970).

    Article  CAS  Google Scholar 

  23. Kim, K. J. & Park, Y. R. Spectroscopic ellipsometry study of optical transitions in Zn1-xCoxO alloys. Appl. Phys. Lett. 81, 1420–1422 (2002).

    Article  CAS  Google Scholar 

  24. Berciu, M. & Bhatt, R. N. Effects of disorder on ferromagnetism in diluted magnetic semiconductors. Phys. Rev. Lett. 87, 107203 (2001).

    Article  CAS  Google Scholar 

  25. Das Sarma, S., Hwang, E. W. & Kaminski, A. Temperature-dependent magnetization in diluted magnetic semiconductors. Phys. Rev. B 67, 155201 (2003).

    Article  Google Scholar 

  26. Wilson, J. A. Systematics of breakdown of Mott insulation in binary transition-metal compounds. Adv. Phys. 21, 143 (1972).

    Article  CAS  Google Scholar 

  27. Saeki, H., Tabata, H. & Kawai, T. Magnetic and electric properties of vanadium doped ZnO films. Solid State Commun. 120, 439–443 (2001).

    Article  CAS  Google Scholar 

  28. Hong, N.Y H., Sakai, J. & Hassini, A. Ferromagnetism at room temperature with a large magnetic moment in anatase V- doped TiO2 thin films. Appl. Phys. Lett. 84, 2602–2604 (2004).

    Article  CAS  Google Scholar 

  29. Venkatesan, M., Fitzgerald, C. B. & Coey, J. M. D. Unexpected magnetism in a dielectric oxide. Nature 430, 630–630 (2004).

    Article  CAS  Google Scholar 

  30. Mattis, D. C. Theory of Magnetism Vol. 1 (Springer, Berlin, 1981).

    Book  Google Scholar 

  31. Yahia, J. Dependence of electrical conductivity and thermoelectric power of pure and aluminium-doped rutile on equilibrium oxygen pressure and temperature. Phys. Rev. 130, 1711–1719 (1963).

    Article  CAS  Google Scholar 

  32. Kohan, A. F., Ceder, G., Morgan, D. & Van de Walle, C. G. First-principles study of native point defects in ZnO. Phys. Rev. B 61, 15019–15027 (2000).

    Article  CAS  Google Scholar 

  33. Stoneham, A. M. Theory of Defects in Solids Ch. 16 (Clarendon, Oxford 1975).

    Google Scholar 

  34. Sonoda, S., Shimizu, S., Sasaki, T., Yamamoto, Y. & Hori, H. Moleclar beam epitaxy of wurtzite (Ga,Mn)N films on sapphire (0001) showing the ferromagnetic behaviour at room temperature. J. Cryst. Growth 237, 1358–1362 (2002).

    Article  Google Scholar 

  35. Hashimoto, M., Zhou, Y. K., Kanamura, M. & Asahi, H. High-temperature (>400K) ferromagnetism in III-V based diluted magnetic semiconductor GaCrN grown by ECR molecular-beam epitaxy. Solid State Commun. 122, 37–39 (2002).

    Article  CAS  Google Scholar 

  36. Wu, S. Y. et al. Synthesis, Characterization and modeling of high-quality ferromagnetic Cr-doped AlN thin films. Appl. Phys. Lett. 82, 3047–3049 (2003).

    Article  CAS  Google Scholar 

  37. Shinde, S. R. et al. Ferromagnetism in laser-deposited anatase Ti1-xCoxO2-δ films. Phys. Rev B 67, 115211 (2003).

    Article  Google Scholar 

  38. Wang, Z. J., Tang, J. K., Tung, L. D., Zhou, W. L. & Spinu, L. Ferromagnetism and transport properties of Fe-doped reduced-rutile TiO2-δ films. J. Appl. Phys. 93, 7870–7872 (2003).

    Article  CAS  Google Scholar 

  39. Coey, J. M. D., Douvalis, A. P., Fitzgerald, C. B. & Venkatesan, M. Ferromagnetism in Fe-doped SnO2 films. Appl. Phys. Lett. 84, 1332–1334 (2004).

    Article  CAS  Google Scholar 

  40. Sharma, P. et al. Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO. Nature Mater. 2, 673–677 (2003).

    Article  CAS  Google Scholar 

  41. Han, S. J. et al. Magnetism in Mn-doped ZnO bulk samples prepared by solid-state reaction. Appl. Phys. Lett. 83, 920–922 (2003).

    Article  CAS  Google Scholar 

  42. Radovanovic, P. V. & Gamelin, D. R. High-temperature ferromagnetism in Ni2+-doped ZnO aggregates prepared from colloidal diluted magnetic semiconductor quantum dots. Phys. Rev. Lett. 91, 157202 (2003).

    Article  Google Scholar 

  43. Kale, S. N. et al. Magnetism in cobalt-doped Cu2O thin films without and without Al, V and Zn codopants. Appl. Phys. Lett. 83, 2100–2102 (2003).

    Article  Google Scholar 

  44. Philip, J., Theodoropolou, N., Berera, G., Moodera, J. S. & Satpati, B. High-temperature ferromagnetism in manganese-doped indium-tin oxide films. Appl. Phys. Lett. 85, 777–779 (2004).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

This work was supported by Science Foundation Ireland as part of the CINSE project. The authors are grateful to James Lunney, Sebastiaan van Dijken, Stefano Sanvito and Plamen Stamenov for their helpful comments.

Author information

Authors and Affiliations

  1. Physics Department, Trinity College, Dublin, 2, Ireland

    J. M. D. Coey, M. Venkatesan & C. B. Fitzgerald

Authors
  1. J. M. D. Coey
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. M. Venkatesan
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. C. B. Fitzgerald
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to J. M. D. Coey.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Coey, J., Venkatesan, M. & Fitzgerald, C. Donor impurity band exchange in dilute ferromagnetic oxides. Nature Mater 4, 173–179 (2005). https://doi.org/10.1038/nmat1310

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat1310

This article is cited by

Search

Advanced 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