Dresden 2011 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 48: CE: Metal-Insulator Transition 2
TT 48.1: Talk
Thursday, March 17, 2011, 10:30–10:45, HSZ 105
The x-ray induced Mott-Anderson scenario in organic charge-transfer salts studied by noise spectroscopy — •Robert Rommel1, Takahiko Sasaki2, and Jens Müller1 — 1Goethe-Universität Frankfurt, SFB/TR49, Frankfurt am Main — 2Institute for Materials Research, Tohoku University, Sendai, Japan
The organic molecular conductors (BEDT-TTF)2X are model systems for low-dimensional metals exhibiting both strong electronic correlations and electron-phonon interactions. With respect to the amount of disorder, different types of metal-to-insulator transitions (MIT) can occur. We will focus on the bandwidth-controlled Mott transition due to external pressure or chemical substitution and disorder-induced carrier localization caused by x-ray irradiation. We will discuss comparative studies of the clean correlation-driven Mott MIT and the Anderson scenario originating from the randomness in the lattice potential. To extract information about the influence of disorder on the electron dynamics we employ noise/fluctuation spectroscopy. The technique was systematically applied after subsequent doses of x-ray irradation of the pristine superconductor κ-(ET)2-Cu[N(CN)2]Br. We find that the increase of insulating behavior in the resistance is accompanied by the emergence of new energy scales pointing to distinct changes in the dynamic properties of the correlated charge carriers.