Local and macroscopic tunneling spectroscopy of Y1-xCaxBa2Cu3O 7-δ films: Evidence for a doping-dependent is or idxy component in the order parameter

A. Sharoni, O. Millo*, A. Kohen, Y. Dagan, R. Beck, G. Deutscher, G. Koren

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Tunneling spectroscopy of epitaxial (110) Y1-xCaxBa2Cu3O 7-δ films reveals a doping-dependent transition from a pure dx2-y2 to dx2-y2 + is or dx2-y2 + idxy order parameter. The subdominant (is or idxy) component manifests itself in a splitting of the zero-bias conductance peak and the appearance of subgap structures. The splitting is seen in the overdoped samples, increases systematically with doping, and is found to be an inherent property of the overdoped films. It was observed in both local tunnel junctions, using scanning tunneling microscopy (STM), and in macroscopic planar junctions, for films prepared by either sputtering or laser ablation. The STM measurements exhibit a fairly uniform splitting size in [110] oriented areas on the order of 10 nm2 but vary from area to area, indicating some doping inhomogeneity. U- and V-shaped gaps were also observed, with good correspondence to the local faceting, a manifestation of the dominant d-wave order parameter.

Original languageEnglish
Article number134526
Pages (from-to)1345261-1345267
Number of pages7
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number13
StatePublished - 1 Apr 2002
Externally publishedYes

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