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TT: Fachverband Tiefe Temperaturen
TT 46: Low-Dimensional Systems: Molecular Conductors
TT 46.4: Vortrag
Dienstag, 1. April 2014, 14:45–15:00, HSZ 204
STM investigations of κ-(BEDT-TTF)2Cu[N(CN)2]Br — •Sandra Diehl1,2,3, Torsten Methfessel1,3, Jens Müller3,4, Michael Lang3,4, and Hans-Joachim Elmers1,2,3 — 1Graduate School Materials Science in Mainz, Staudingerweg 9, 55128 Mainz — 2Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz — 3SFB/TR 49 — 4Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main
We investigate the organic charge-transfer salt κ-(BEDT-TTF)2Cu[N(CN)2]Br as an example for an organic superconductor. The superconducting properties strongly deviate from BCS theory but resemble the properties of high-Tc cuprates which has been attributed to their two dimensional structure leading to electronic correlation effects [1]. In order to understand their electronic properties we measured temperature dependent differential conductivity spectra using scanning tunneling spectroscopy. With this method the shape of the superconducting gap can be determined. In addition to the superconducting gap of the expected size we observe a second, much wider gap indicating a surprisingly large correlation effect. Furthermore, we present STM images showing the alternating structure of conducting and insulating layers. All investigations were done under UHV-conditions (5 · 10−11 mbar) using a low temperature scanning tunneling microscope. The surface of the crystals was prepared by in-situ cleaving.
R. H. McKenzie, Science 278, 820 (1997)