Letter | Published:

Detection of magnetic circular dichroism using a transmission electron microscope

Nature volume 441, pages 486488 (25 May 2006) | Download Citation

Subjects

Abstract

A material is said to exhibit dichroism if its photon absorption spectrum depends on the polarization of the incident radiation. In the case of X-ray magnetic circular dichroism (XMCD), the absorption cross-section of a ferromagnet or a paramagnet in a magnetic field changes when the helicity of a circularly polarized photon is reversed relative to the magnetization direction. Although similarities between X-ray absorption and electron energy-loss spectroscopy in a transmission electron microscope (TEM) have long been recognized, it has been assumed that extending such equivalence to circular dichroism would require the electron beam in the TEM to be spin-polarized. Recently, it was argued on theoretical grounds that this assumption is probably wrong1. Here we report the direct experimental detection of magnetic circular dichroism in a TEM. We compare our measurements of electron energy-loss magnetic chiral dichroism (EMCD) with XMCD spectra obtained from the same specimen that, together with theoretical calculations, show that chiral atomic transitions in a specimen are accessible with inelastic electron scattering under particular scattering conditions. This finding could have important consequences for the study of magnetism on the nanometre and subnanometre scales, as EMCD offers the potential for such spatial resolution down to the nanometre scale while providing depth information—in contrast to X-ray methods, which are mainly surface-sensitive.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    & A proposal for dichroic experiments in the electron microscope. Ultramicroscopy 96, 463–468 (2003)

  2. 2.

    et al. X-ray circular dichroism as a probe of orbital magnetization. Phys. Rev. Lett. 68, 1943–1946 (1992)

  3. 3.

    et al. X-ray circular dichroism and local magnetic fields. Phys. Rev. Lett. 70, 694–697 (1993)

  4. 4.

    et al. Experimental proof of magnetic X-ray dichroism. Phys. Rev. B 34, 6529–6531 (1986)

  5. 5.

    et al. Absorption of circularly polarized X-rays in iron. Phys. Rev. Lett. 58, 737–740 (1987)

  6. 6.

    et al. Experimental confirmation of the X-ray magnetic circular dichroism sum rules for iron and cobalt. Phys. Rev. Lett. 75, 152–155 (1995)

  7. 7.

    et al. Spectroscopic identification and direct imaging of interfacial magnetic spins. Phys. Rev. Lett. 87, 247201–247204 (2001)

  8. 8.

    et al. Enhanced orbital magnetic moment on co atoms in Co/Pd multilayers: a magnetic circular X-ray dichroism study. Phys. Rev. Lett. 69, 2307–2310 (1992)

  9. 9.

    et al. Enhancement of orbital magnetism at surfaces: Co on Cu(100). Phys. Rev. Lett. 75, 1602–1605 (1995)

  10. 10.

    et al. Magnetic phase transition in Co/Cu/Ni/Cu(100) and Co/Fe/Ni/Cu(100). Phys. Rev. Lett. 91, 147202–147205 (1993)

  11. 11.

    et al. Microscopic origin of magnetic anisotropy in Au/Co/Au probed with X-ray magnetic circular dichroism. Phys. Rev. Lett. 75, 3752–3755 (1995)

  12. 12.

    & Magnetic moments in as-deposited and annealed Ni layers on Fe(001): an x-ray-dichroism study. Phys. Rev. B 53, 3409–3414 (1996)

  13. 13.

    Exploring the microscopic origin of magnetic anisotropies with X-ray magnetic circular dichroism (XMCD) spectroscopy. J. Magn. Magn. Mater. 200, 470–497 (1999)

  14. 14.

    X-ray magnetic circular dichroism spectroscopy of transition metal thin films. J. Electron Spectrosc. Related Phenom. 75, 253–272 (1995)

  15. 15.

    & Magnetic linear dichroism in electron energy loss spectroscopy. J. Appl. Phys. 81, 5087–5089 (1997)

  16. 16.

    Near edge electron energy loss spectroscopy: comparison to X-ray absorption. Jpn. J. Appl. Phys. 32 (suppl. 2), 176–181 (1992)

  17. 17.

    & Theory of image formation by inelastically scattered electrons in the electron microscope. Adv. Electron. Electron Phys. 65, 173–227 (1985)

  18. 18.

    , , , & An Augmented Plane Wave and Local Orbitals Program for Calculating Crystal Properties (ed. Schwarz, K.) (Technical University of Wien, Vienna, 2001)

  19. 19.

    , & Observation of ionization in a crystal interferometer. Phys. Rev. Lett. 85, 1847–1850 (2000)

  20. 20.

    et al. Theory of orientation sensitive near-edge fine structure core-level spectroscopy. Phys. Rev. B 59, 10959–10969 (1999)

  21. 21.

    & Mesoscopic texture in manganites. Phys. Today 56, 25–30 (2003)

Download references

Acknowledgements

We thank E. Bauer and S. Buehler-Paschen for discussions. This work was supported by the European Union under the project CHIRALTEM. Author Contributions P.S. and C.H. had the idea to do this experiment and developed the principles; P.S. wrote the manuscript; S.R. performed the experiment on the TEM and adapted the EMCD program; J.R. was the principal developer of the EMCD program; J.K. helped substantially in debugging the EMCD program; P.N. generalized two programs contained in the WIEN2k package that were used in the EMCD program and helped in its debugging and implementation; E.C. produced and characterized the TEM substrates; M.F. grew the iron films and ran XMCD and magneto-optic Kerr effect experiments; G.P. and G.R. coordinated the work at the synchrotron and the XMCD data analysis. All authors discussed the results and contributed to the manuscript.

Author information

Affiliations

  1. Service Centre for Transmission Electron Microscopy, Wiedner Hauptstraße 8-10/052, and Institut für Festkörperphysik, Wiedner Hauptstraße 8-10/138, Technische Universität Wien, A-1040 Wien, Austria

    • P. Schattschneider
    • , S. Rubino
    •  & C. Hébert
  2. Institute of Physics ASCR, Cukrovarnická 10, 16253 Praha 6, Czech Republic

    • J. Rusz
    • , J. Kuneš
    •  & P. Novák
  3. TASC INFM-CNR National Laboratory, Area Science Park, S.S.14, Km 163.5, I-34012 Trieste, Italy

    • E. Carlino
    • , M. Fabrizioli
    • , G. Panaccione
    •  & G. Rossi
  4. Università degli Studi di Trieste, Piazzale Europa 1, I-34100 Trieste, Italy

    • M. Fabrizioli
  5. Dipartimento di Fisica dell'Università di Modena e Reggio Emilia–I-41100 Modena, Italy

    • G. Rossi

Authors

  1. Search for P. Schattschneider in:

  2. Search for S. Rubino in:

  3. Search for C. Hébert in:

  4. Search for J. Rusz in:

  5. Search for J. Kuneš in:

  6. Search for P. Novák in:

  7. Search for E. Carlino in:

  8. Search for M. Fabrizioli in:

  9. Search for G. Panaccione in:

  10. Search for G. Rossi in:

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Corresponding author

Correspondence to P. Schattschneider.

Supplementary information

PDF files

  1. 1.

    Supplementary Notes

    This file contains Supplementary Discussion, Supplementary Figures 1–3 and Supplementary Equations. This file also contains additional references.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nature04778

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.