Disorder-induced gap in the normal density of states of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br

Sandra Diehl; Torsten Methfessel; Ulrich Tutsch; Jens Müller; Michael Lang; Michael Huth; Martin Jourdan; Hans-Joachim Elmers

doi:10.1088/0953-8984/27/26/265601

Disorder-induced gap in the normal density of states of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br

J Phys Condens Matter. 2015 Jul 8;27(26):265601. doi: 10.1088/0953-8984/27/26/265601. Epub 2015 Jun 15.

Authors

Sandra Diehl¹, Torsten Methfessel, Ulrich Tutsch, Jens Müller, Michael Lang, Michael Huth, Martin Jourdan, Hans-Joachim Elmers

Affiliation

¹ Graduate School Materials Science In Mainz, Staudingerweg 9, 55128 Mainz, Germany. Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany.

PMID: 26076168
DOI: 10.1088/0953-8984/27/26/265601

Abstract

The local density of states (DOS) of the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, measured by scanning tunneling spectroscopy on in situ cleaved surfaces, reveals a logarithmic suppression near the Fermi edge persisting above the critical temperature T(c). The experimentally observed suppression of the DOS is in excellent agreement with a soft Hubbard gap as predicted by the Anderson-Hubbard model for systems with disorder. The electronic disorder also explains the diminished coherence peaks of the quasi-particle DOS below T(c).