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Tunnel junctions with multiferroic barriers

Nature Materials volume 6, pages 296302 (2007) | Download Citation

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Abstract

Multiferroics are singular materials that can exhibit simultaneously electric and magnetic orders. Some are ferroelectric and ferromagnetic and provide the opportunity to encode information in electric polarization and magnetization to obtain four logic states. However, such materials are rare and schemes allowing a simple electrical readout of these states have not been demonstrated in the same device. Here, we show that films of La0.1Bi0.9MnO3 (LBMO) are ferromagnetic and ferroelectric, and retain both ferroic properties down to a thickness of 2 nm. We have integrated such ultrathin multiferroic films as barriers in spin-filter-type tunnel junctions that exploit the magnetic and ferroelectric degrees of freedom of LBMO. Whereas ferromagnetism permits read operations reminiscent of magnetic random access memories (MRAM), the electrical switching evokes a ferroelectric RAM write operation. Significantly, our device does not require the destructive ferroelectric readout, and therefore represents an advance over the original four-state memory concept based on multiferroics.

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Acknowledgements

We thank M. Varela and E. Jacquet for their help in sample fabrication and N. D. Mathur, J. F. Scott and H. Kohlstedt for fruitful discussions. This study was partially supported by the Picasso France–Spain program, the CICYT of the Spanish Government Projects NAN2004-9094 and MAT2005-05656, FEDER, the E.U. Marie Curie mobility program, the project FEMMES of the French Agence National de la Recherche (ANR-05-1-45147), the European Science Foundation THIOX network and the E.U. STREPs Nanotemplates (Contract NMPA4-2004-505955) and MaCoMuFi (Contract FP6-NMP3-CT-2006-033221).

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Affiliations

  1. Unité Mixte de Physique CNRS/Thales and Université Paris-Sud, Route départementale 128, 91767 Palaiseau, France

    • Martin Gajek
    • , Stéphane Fusil
    • , Karim Bouzehouane
    • , Agnès Barthélémy
    •  & Albert Fert
  2. Institut de Ciència de Materials de Barcelona, CSIC, Campus de la Universitat Autonoma de Barcelona, 08193 Bellaterra, Spain

    • Martin Gajek
    •  & Josep Fontcuberta
  3. Institut d’Electronique Fondamentale, CNRS, Université Paris-Sud, 91405 Orsay, France

    • Manuel Bibes

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The authors declare no competing financial interests.

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Correspondence to Manuel Bibes.

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https://doi.org/10.1038/nmat1860

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