Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 46: Low-Dimensional Systems: Molecular Conductors
TT 46.3: Vortrag
Dienstag, 1. April 2014, 14:30–14:45, HSZ 204
Charge-carrier dynamics at the Mott transition in κ-(BEDT-TTF)2X-Salts — •Benedikt Hartmann1, David Zielke1, Jana Polzin1, Robert Rommel1, John A. Schlueter2, Takahiko Sasaki3, and Jens Müller1 — 1Institute of Physics, Goethe University Frankfurt, Germany — 2Materials Science Division, Argonne National Laboratory, Argonne, IL, USA — 3Institute for Materials Research, Tohoku University, Sendai, Japan
The nature of criticality at the Mott transition recently has been in the focus of intense experimental and theoretical research. The quasi-2D organic charge-transfer salts κ-(ET)2X are considered as model systems for studying the Mott metal-insulator transition (MIT) in reduced dimensions. We investigated partially deuterated κ-[(H8-ET)0.2(D8-ET)0.8]2Cu[N(CN)2]Br, which is located very close to the critical pressure p0 and further utilized the possibility to reversibly tune the ’chemical pressure’ by employing different cooling rates shifting the system to the critical region of the generalized phase diagram. By means of fluctuation (noise) spectroscopy as a powerful new tool for studying charge-carrier dynamics without injecting additional electrons, we observe a pronounced and sudden slowing down of the dynamics near the finite-temperature critical endpoint (p0, T0) of the Mott transition. A striking divergence of the low-frequency resistance fluctuations at T0 for certain cooling rates is accompanied by a signature in higher-order statistical moments (second spectrum) being a hint to spatial correlations. We dicuss this in terms of glassiness of the electronic system which may be an universal feature of MITs.