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Quantized magnetoresistance in atomic-size contacts

Nature Nanotechnology volume 2, pages 171–175 (2007)Cite this article

Abstract

When the dimensions of a metallic conductor are reduced so that they become comparable to the de Broglie wavelengths of the conduction electrons, the absence of scattering results in ballistic electron transport1 and the conductance becomes quantized2,3,4. In ferromagnetic metals, the spin angular momentum of the electrons results in spin-dependent conductance quantization5,6,7 and various unusual magnetoresistive phenomena8,9,10,11,12. Theorists have predicted a related phenomenon known as ballistic anisotropic magnetoresistance (BAMR)13. Here we report the first experimental evidence for BAMR by observing a stepwise variation in the ballistic conductance of cobalt nanocontacts as the direction of an applied magnetic field is varied. Our results show that BAMR can be positive and negative, and exhibits symmetric and asymmetric angular dependences, consistent with theoretical predictions.

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Figure 1: Ballistic transport measurements for Co nanocontacts.
Figure 2: Time-dependent quantum conductance.
Figure 3: Angular dependence of ballistic conductance.
Figure 4: Results of a tight-binding model.

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Acknowledgements

This work was supported by the Nebraska Research Initiative and the National Science Foundation through the Materials Research Science and Engineering Center (grant DMR-0213808) and the Chemistry Division (grant CHE-0518644). B.D. acknowledges support from a ‘Chaire d'excellence’ fellowship of the French ANR.

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Authors and Affiliations

  1. Department of Physics and Astronomy, University of Nebraska, Lincoln, 68588, Nebraska, USA

    Andrei Sokolov & Evgeny Y. Tsymbal

  2. Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, 68588, Nebraska, USA

    Andrei Sokolov, Chunjuan Zhang, Evgeny Y. Tsymbal & Jody Redepenning

  3. Department of Chemistry, University of Nebraska, Lincoln, 68588, Nebraska, USA

    Chunjuan Zhang & Jody Redepenning

  4. Institut de Physique et de Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 CNRS-ULP, Strasbourg, 67034, France

    Bernard Doudin

Authors
  1. Andrei Sokolov
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  2. Chunjuan Zhang
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  3. Evgeny Y. Tsymbal
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  4. Jody Redepenning
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  5. Bernard Doudin
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Contributions

A.S. and C.Z. performed the experiment and analysed the data. E.Y.T. performed the theory, J.R. provided guidance for the electrochemistry part, and B.D. conceived and designed the experiment.

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Correspondence to Andrei Sokolov or Bernard Doudin.

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The authors declare no competing financial interests.

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Supplementary figures S1—S4 (PDF 234 kb)

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Sokolov, A., Zhang, C., Tsymbal, E. et al. Quantized magnetoresistance in atomic-size contacts. Nature Nanotech 2, 171–175 (2007). https://doi.org/10.1038/nnano.2007.36

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