Tunneling into Andreev bound states of YBa2Cu3O7: Observation of broken time-reversal symmetry

L. H. Greene, M. Covington, M. Aprili, E. Paraoanu

Research output: Contribution to journalArticlepeer-review

Abstract

Planar tunneling is a powerful spectroscopic probe of superconducting YBa2Cu3O7 (YBCO). In YBCO/I/Cu junctions, an organic monolayer is used to form the insulator. The reproducible dependences of the tunneling conductance on temperature, magnetic field and ion-induced disorder show that the zero-bias conductance peak (ZBCP) is an Andreev bound state, of the d-wave order parameter. In zero applied field the ZBCP splits at T∼8 K, signifying a phase transition into a state with spontaneously broken time-reversal symmetry. An applied field induces further splitting that saturates at fields of order 2-3 T. These data support a theoretical model that invokes the formation of sub-dominant order parameter.

Original languageEnglish (US)
Pages (from-to)2021-2025
Number of pages5
JournalJournal of Physics and Chemistry of Solids
Volume59
Issue number10-12
DOIs
StatePublished - 1998

Keywords

  • A. Thin films
  • Electronic transport
  • High-t superconductivity
  • Highly correlated electron systems
  • Surfaces and interfaces
  • Tunneling

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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