Scaling behavior of point contacts between a tungsten tip and the heavy-fermion superconductors
We investigated metallic point contacts between a tungsten tip and the superconducting heavy-fermion compounds. On lowering the temperature to below T sub(c) the contact resistance drops by delta R. Usually this change in resistance is interpreted by the Andreev-reflection process at the normal-supe...
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Veröffentlicht in: | Journal of Low Temperature Physics 1996-10, Vol.105 (1-2), p.37-65 |
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Sprache: | eng |
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Zusammenfassung: | We investigated metallic point contacts between a tungsten tip and the superconducting heavy-fermion compounds. On lowering the temperature to below T sub(c) the contact resistance drops by delta R. Usually this change in resistance is interpreted by the Andreev-reflection process at the normal-superconducting interface. However, we found that delta R does not scale with the inverse area of the orifice - as expected for Andreev reflection - but with the inverse radius and the specific resistivity in the normal state. Such a behaviour is characteristic for Maxwell's resistance being suppressed in the superconducting heavy-fermion phase. Additionally, the residual contact resistance at zero-bias is strongly enhanced compared to the ballistic Sharvin contribution. We discuss the possible microscopic origin for the reduced or even absent Andreev-hole current and the enhanced residual resistance. |
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ISSN: | 0022-2291 1573-7357 |
DOI: | 10.1007/bf00754627 |