Article abstract
Nature Materials 4, 62 - 67 (2004)
Published online: 12 December 2004 | doi:10.1038/nmat1280
Subject Categories: Magnetic materials | Characterisation and analytical techniques
Full bulk spin polarization and intrinsic tunnel barriers at the surface of layered manganites
J. W. Freeland1, K. E. Gray2, L. Ozyuzer2,3, P. Berghuis2, Elvira Badica2, J. Kavich1, H. Zheng2 & J. F. Mitchell2
Abstract
Transmission of information using the spin of the electron as well as its charge requires a high degree of spin polarization at surfaces. However, at surfaces this degree of polarization can be quenched by competing interactions. Using a combination of surface-sensitive X-ray and tunnelling probes, we show for the quasi-two-dimensional bilayer manganites that only the outermost Mn–O bilayer is affected: it is a 1-nm-thick insulator that exhibits no long-range ferromagnetic order, whereas the next bilayer displays the full spin polarization of the bulk. Such an abrupt localization of the surface effects is due to the two-dimensional nature of the layered manganite, and the loss of ferromagnetism is attributed to weakened double exchange in the reconstructed surface bilayer and a resultant antiferromagnetic phase. The creation of a well-defined surface insulator atop a fully spin-polarized bulk demonstrates the ability of two of the most demanding components of an ideal magnetic tunnel junction to self-assemble naturally.
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Permanent address: Department of Phyisics, Izmir Institute of Technology, Izmir, TR-35437, Turkey
Correspondence to: J. W. Freeland1 e-mail: freeland@anl.gov
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