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The signature of chemical valence in the electrical conduction through a single-atom contact


Fabrication of structures at the atomic scale is now possible using state-of-the-art techniques for manipulating individual atoms1, and it may become possible to design electrical circuits atom by atom. A prerequisite for successful design is a knowledge of the relationship between the macroscopic electrical characteristics of such circuits and the quantum properties of the individual atoms used as building blocks. As a first step, we show here that the chemical valence determines the conduction properties of the simplest imaginable circuit—a one-atom contact between two metallic banks. The extended quantum states that carry the current from one bank to the other necessarily proceed through the valence orbitals of the constriction atom. It thus seems reasonable to conjecture that the number of current-carrying modes (or ‘channels’) of a one-atom contact is determined by the number of available valence orbitals, and so should strongly differ for metallic elements in different series of the periodic table. We have tested this conjecture using scanning tunnelling microscopy and mechanically controllable break-junction techniques2,3 to obtain atomic-size constrictions for four different metallic elements (Pb, Al, Nb and Au), covering a broad range of valences and orbital structures. Our results demonstrate unambiguously a direct link between valence orbitals and the number of conduction channels in one-atom contacts.

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Figure 1: Typical conductance G as a function of distance, recorded during a continuous opening of the samples, for four different metals.
Figure 2: Measured current-voltage characteristics (plotting symbols) of five different configurations of a Pb sample at 1.5 K using STM, and best numerical fits (lines).
Figure 3: Localized orbitals model for electrical conduction through one-atom contacts.


  1. Crommie, M. F., Lutz, C. P. & Eigler, D. M. Confinement of electrons to quantum corrals on a metal surface. Science 262, 218– 220 (1993).

    Article  ADS  CAS  Google Scholar 

  2. van Ruitenbeek, J. M. in Mesoscopic Electron Transport (eds Sohn, L. L., Kouwenhoven, L. P. & Schön, G.) 549–579 (Kluwer Academic, Dordrecht, (1997)).

    Book  Google Scholar 

  3. van Ruitenbeek, J. M. et al. Adjustable nanofabricated atomic size contacts. Rev. Sci. Instrum. 67, 108–111 (1996).

    Article  ADS  CAS  Google Scholar 

  4. Landauer, R. Electrical resistance of disordered one-dimensional lattices. Phil. Mag. 21, 863–867 ( 1970).

    Article  ADS  CAS  Google Scholar 

  5. Scheer, E., Joyez, P., Esteve, D., Urbina, C. & Devoret, M. H. Conduction channel transmissions of atomic-size aluminum contacts. Phys. Rev. Lett. 78, 3535– 3538 (1997).

    Article  ADS  CAS  Google Scholar 

  6. Octavio, M., Tinkham, M., Blonder, G. E. & Klapwijk, T. M. Subharmonic energy-gap structure in superconducting constrictions. Phys. Rev. B 27, 6739–6746 (1983).

    Article  ADS  Google Scholar 

  7. Averin, D. & Bardas, A. AC Josephson effect in a single quantum channel. Phys. Rev. Lett. 75, 1831– 1834 (1995).

    Article  ADS  CAS  Google Scholar 

  8. Cuevas, J. C., Martín-Rodero, A. & Levy Yeyati, A. Hamiltonian approach to the transport properties of superconducting quantum point contacts. Phys. Rev. B 54, 7366–7379 (1996).

    Article  ADS  CAS  Google Scholar 

  9. Bratus, E. N., Shumeiko, V. S., Bezuglyi, E. V. & Wendin, G. dc-current transport and ac Josephson effect in quantum junctions at low voltage. Phys. Rev. B 55, 12666– 12677 (1997).

    Article  ADS  CAS  Google Scholar 

  10. Agraït, N., Rodrigo, J. G. & Vieira, S. Conductance steps and quantization in atomic-size contacts. Phys. Rev. B 47, 12345– 12348 (1996).

    Article  ADS  Google Scholar 

  11. Rubio, G., Agraït, N. & Vieira, S. Atomic-sized metallic contacts: mechanical properties and electronic transport. Phys. Rev. Lett. 76, 2302–2305 (1996).

    Article  ADS  CAS  Google Scholar 

  12. Krans, J. M., van Ruitenbeek, J. M., Fisun, V. V., Yanson, I. K. & de Jongh, L. J. The signature of conductance quantization in metallic point contacts. Nature 375 , 767–769 (1995).

    Article  ADS  CAS  Google Scholar 

  13. Landman, U., Luedtke, W. D., Salisbury, B. E. & Whetten, R. L. Reversible manipulations of room temperature mechanical and quantum transport properties in nanowire junctions. Phys. Rev. Lett. 77, 1362–1365 (1996).

    Article  ADS  CAS  Google Scholar 

  14. Todorov, T. N. & Sutton, A. P. Jumps in electronic conductance due to mechanical instabilities. Phys. Rev. Lett. 70, 2138–2141 (1993).

    Article  ADS  CAS  Google Scholar 

  15. Beenakker, C. W. J. Quantum transport in semiconductor superconductor microjunctions. Phys. Rev. B 46, 12841–12844 (1992).

    Article  ADS  CAS  Google Scholar 

  16. Cuevas, J. C., Levy Yeyati, A. & Martín-Rodero, A. Microscopic origin of the conducting channels in metallic atomic-size contacts. Phys. Rev. Lett. 80, 1066–1069 (1998).

    Article  ADS  CAS  Google Scholar 

  17. Levy Yeyati, A., Martín-Rodero, A. & Flores, F. Conductance quantization and electron resonances in sharp tips and atomic size contacts. Phys. Rev. B 56, 10369–10372 (1997).

    Article  ADS  Google Scholar 

  18. Lang, N. D. Resistance of atomic wires. Phys. Rev. B 52, 5335–5342 (1995).

    Article  ADS  CAS  Google Scholar 

  19. Wan, C. C., Mozos, J.-L., Taraschi, G., Wang, J. & Guo, H. Quantum transport through atomic wires. Appl. Phys. Lett. 71, 419– 421 (1997).

    Article  ADS  CAS  Google Scholar 

  20. Brandbyge, M., Sørensen, M. R. & Jacobsen, K. W. Conductance eigenchannels in nanocontacts. Phys. Rev. B 56, 14956– 14959 (1997).

    Article  ADS  CAS  Google Scholar 

  21. Belzig, W., Bruder, C. & Schön, G. Local density of states in a dirty normal metal connected to a superconductor. Phys. Rev. B 54, 9443 –9448 (1996).

    Article  ADS  CAS  Google Scholar 

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We thank D. Esteve and M. H. Devoret for discussions and C. Sürgers for graphics preparation; N.A. and G.R.B. thank S. Vieira for discussions and support. The work was supported in part by the Deutsche Forschungsgemeinschaft (DFG), the Spanish CICYT, “Stichting FOM” (NWO) and the Bureau National de Métrologie (BNM).

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Correspondence to Elke Scheer.

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Scheer, E., Agraït, N., Cuevas, J. et al. The signature of chemical valence in the electrical conduction through a single-atom contact. Nature 394, 154–157 (1998).

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