Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 80: Low-Dimensional Systems - Poster Session

TT 80.16: Poster

Mittwoch, 2. April 2014, 15:00–19:00, P2

Statistical properties of the charge-carrier dynamics at the Mott critical endpoint in κ-(BEDT-TTF)₂X-Salts — •David Zielke¹, Benedikt Hartmann¹, 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 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 can be reversibly tuned through the critical region in the generalized phase diagram by employing different cooling rates which has a crucial effect on the ratio of bandwith W to on-site Coulomb repulsion U. On this poster, we describe our statistical analysis of the resistance fluctuations by means of time-resolved transport measurements in the vicinity of the finite-T critical endpoint (p₀,T₀). Utilizing a fast data acquisition card in combination with a self-written software we derive the resistance noise power spectral density and higher-order statistical moments (second spectrum). At T₀, we observe a drastic enhancement and slowing down of the low-frequency resistance fluctuations for certain cooling rates together with a frequency dependent signature in the second spectrum. We interpret our observations in terms of a glassy electronic system possibly being universal for MITs.