Coherent particle response of two-dimensional organic conductors upon crossing the Mott transition

• Published in: Journal of physics. Conference series Vol. 200; no. 1; p. 012029
• Main Authors: Dressel, M, Dumm, M, Drichko, N, Méziere, C, Batail, P
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2010
• Subjects: Charge transfer; Conductors; Electrodynamics; Elementary excitations; Energy gap; Insulators; Metal-insulator transition; Organic charge transfer salts; Physics; Room temperature; Temperature dependence
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/200/1/012029

The two-dimensional organic charge-transfer salt κ-(BEDT-TTF)2Cu[N(CN)2]-BrxCl1–x is tuned across the metal-insulator transition by varying the Br content. Temperature dependent measurements of the optical conductivity yield information on the electrodynamics of the half-filled correlated electron system. At room temperature a broad incoherent response is observed with no clear Drude peak. As the temperature drops below 50 K, an energy gap develops in the Cl-rich samples which grows to approximately 1000 cm−1 for T → 0. With increasing Br concentration spectral weight shifts into the gap region and eventually fills it up completely. A Drude-like component develops due to the coherent quasiparticles.