Gap anisotropy and Fermi velocity in oriented YBa2Cu3O7-δ from point contact spectroscopy

Nir Hass*, D. Ilzycer, G. Deutscher, G. Desgardin, I. Monot, M. Weger

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Point contact spectroscopy measurements on YBa2Cu3O7-δ textured ceramics are presented. The I(V) curves measured along the Copper-Oxygen plane direction at 4.2K are characteristic of the Andreev reflection phenomenon, with a sharp break at the gap edge. This allows a rather precise determination of the in plane gap, Δ=19±1mev. Subgap structure suggests the existence of a smaller gap for some orientations in the CuO plane, of the order of 12mev. Preliminary results of measurements performed at higher temperature suggest the possibility of a non BCS s-wave temperature dependence of the gap, Δ(T). The data enabled us to set a lower bound to the in plane Fermi velocity in YBa2Cu3O7-δ: vF≥7×107cm/sec, considerably higher than band structure calculations. We discuss the importance of vF with respect to theoretical explanations for High Temperature Superconductivity.

Original languageEnglish
Pages (from-to)85-88
Number of pages4
JournalPhysica C: Superconductivity and its Applications
Volume209
Issue number1-3
DOIs
StatePublished - 20 Apr 1993

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