Probing the Local Effects of Magnetic Impurities on Superconductivity
10.1126/science.275.5307.1767
Crossref journal-article
American Association for the Advancement of Science (AAAS)
Science (221)
Abstract

The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor's energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra.

Bibliography

Yazdani, A., Jones, B. A., Lutz, C. P., Crommie, M. F., & Eigler, D. M. (1997). Probing the Local Effects of Magnetic Impurities on Superconductivity. Science, 275(5307), 1767–1770.

Authors 5
  1. Ali Yazdani (first)
  2. B. A. Jones (additional)
  3. C. P. Lutz (additional)
  4. M. F. Crommie (additional)
  5. D. M. Eigler (additional)
References 23 Referenced 469
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  11. For this and all other tunneling spectra reported here we examined the effect of the tip by repeating the measurements with different tips prepared from the same Au wire by (i) allowing it to collide with the Nb surface or (ii) performing field emission with it such that there was a significant change in the microscopic configuration of its outermost atoms. The results of these experiments show that the Au tips contribute little to the features in the spectra measured over the narrow range of energies near the Fermi level E F where we are interested in the DOS. Furthermore our results were insensitive to the value of initial junction impedance (which determines the tip height) over 3.5 decades (10 8 to 5 × 10 5 ohms) except for a constant scaling factor.
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  17. We have not made a more detailed comparison of the radial dependence between the measurement and the model calculation. Such a comparison would require us to taken into account the details of the adatom geometry that is the fact that at small lateral tip displacements ( r < 4 Å) most of the tunneling current is channeled through the impurity site [for example see N. D. Lang Phys. Rev. Lett. 56 1164 (1986)].
  18. Our model predicts a local electron-hole asymmetry that oscillates and decays as a function of distance from the impurity. The l = 0 amplitude remains constant but its contribution decays as a function of r. Gaussian averaging of the model calculation over typical distances averaged by STM causes a nonoscillatory but decaying asymmetry in the region near the impurity.
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  20. Varying the parameters of the calculation we find that for a = 2.5 Å we can fit the data using U ranging from 0 to 0.15 E F while allowing J to vary by 5%. The bound excitation energy that is the peak location in the data is a very sensitive function of J.
  21. Flatte M. E. Byers J. M. Phys. Rev. Lett. in press.
  22. Salkola M. I. Balatsky A. V. Schrieffer J. R. Phys. Rev. B in press.
  23. We thank the authors of (17) and (18) for their interest in our experiment and thank D.-H Lee D. J. Scalapino and M. Tinkham for fruitful discussions.
Dates
Type When
Created 23 years ago (July 27, 2002, 5:45 a.m.)
Deposited 1 year, 7 months ago (Jan. 12, 2024, 10:58 p.m.)
Indexed 3 days, 21 hours ago (Aug. 21, 2025, 2:21 p.m.)
Issued 28 years, 5 months ago (March 21, 1997)
Published 28 years, 5 months ago (March 21, 1997)
Published Print 28 years, 5 months ago (March 21, 1997)
Funders 0

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@article{Yazdani_1997, title={Probing the Local Effects of Magnetic Impurities on Superconductivity}, volume={275}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.275.5307.1767}, DOI={10.1126/science.275.5307.1767}, number={5307}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Yazdani, Ali and Jones, B. A. and Lutz, C. P. and Crommie, M. F. and Eigler, D. M.}, year={1997}, month=mar, pages={1767–1770} }