Electron tunneling into A15 and B1 superconductors
| Autor: | W. Bangert, M. Gurvitch, J. Remeika, J.R. Rowell, H. Rietschell, U. Schneider, J. Geerk, F. Gompf |
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| Rok vydání: | 1985 |
| Předmět: |
Superconductivity
Materials science Condensed matter physics Phonon Fermi level General Engineering chemistry.chemical_element Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Spectral line Condensed Matter::Materials Science symbols.namesake chemistry Condensed Matter::Superconductivity symbols Density of states Thin film Tin Quantum tunnelling |
| Zdroj: | Physica B+C. 135:187-197 |
| ISSN: | 0378-4363 |
| Popis: | We have prepared high quality tunnel junctions on thin films of Nb 3 Sn, Nb 3 Ge, Nb 3 Al and TiN with artificial tunnel barriers of Al-oxide and AlZr-oxide. The Nb 3 Sn/AlZr-oxide/Pb tunnel junctions prepared on Sn-deficient material showed no measurable proximity effect. Whereas the tunnel spectra of Sn deficient A15 NbSn could be satisfactorily analyzed by the standard Rowell-McMillan inversion procedure, the reduced density of states of the stoichiometric samples exhibited characteristic deformations in form of an overswing at energies far above the highest phonon energy. These deformations can be fitted by proximity analysis but it is shown that they can also be referred to the influence of an electronic density of states which is strongly structured in the range of phonon energies near the Fermi level. A very similar behavior is found for Nb 3 Ge and to a smaller extent for Nb 3 Al. Furthermore first tunneling results are presented for the B1 superconductors NbN and TiN. For NbN the Eliashberg function in the energy region of the acoustic phonons was determined and an upper limit for the coupling strength of the optical phonons is estimated. For TiN we show second derivative data. The energetic location of the minima in these curves agrees well with the position of maxima of the photon density of states. |
| Databáze: | OpenAIRE |
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