Volume 84, Number 4, November 2008
|Number of page(s)||5|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||10 November 2008|
Tc-dependence of energy gap and asymmetry of coherence peaks in NdBa2Cu3O7- superconductors
Institute of Experimental Physics, University of Saarland - D-66041 Saarbruecken, Germany, EU
2 Institute of Solid State Physics, Forschungzentrum Karlsruhe - D-76021 Karlsruhe, Germany, EU
Accepted: 13 October 2008
We report here the results of scanning tunneling spectroscopy experiments performed on hole-doped NdBa2Cu3O7- single crystals of Tc values of 76 K, 93.5 K and 95.5 K. The energy gaps are observed to be increasing with decreasing Tc values. The coherence peaks are asymmetric with the peaks at the filled states being larger than those at the empty ones. The asymmetry increases with decreasing Tc. The observed asymmetry and its Tc-dependence can be explained by considering the Mott insulating nature of the material at the undoped state.
PACS: 74.72.Bk – Y-based cuprates / 74.25.Jb – Electronic structure / 74.50.+r – Tunneling phenomena; point contacts, weak links, Josephson effects
© EPLA, 2008
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