Transport studies at the Mott transition of the two-dimensional organic metal κ-(BEDT-TTF)2Cu[N(CN)2]BrxCl1−x


Transport studies at the Mott transition of the two-dimensional organic metal κ-(BEDT-TTF)2Cu[N(CN)2]BrxCl1−x

Yasin, S.; Dumm, M.; Salameh, B.; Batail, P.; Mézière, C.; Dressel, M.

The two-dimensional organic conductor κ-(BEDT-TTF)2Cu[N(CN)2]BrxCl1−x undergoes a transition from an insulator to a superconductor upon substituting Cl by Br. We have performed in and out-of-plane electric-transport measurements on the alloyed series with x = 20%, 40%, 70%, 80%, 85%, and 90% as a function of temperature in order to explore the bandwidth-controlled phase transition between the Mott insulator and the Fermi-liquid. All crystals exhibit a similar semiconducting behavior of ρ(T) from room temperature down to 100 K. Below approximately 50 K, a metal-to-insulator transition is found for compounds with x < 70%. Out of this Mott insulating state, magnetic order develops below TN ≈ 25 K. The Br-rich samples cross a bad-metal regime before they become coherent metals and eventually superconducting at Tc ≈ 12 K. For these systems the resistivity at Tc ≤ T ≤ T0 reveals a ρ(T) ∝ T2 dependence associated with a strongly correlated Fermi-liquid, limited by some characteristic temperature T0. The conclusions are corroborated by data from microwave, magnetic and optical experiments.

  • European Physical Journal B 79(2011), 383-390

Permalink: https://www.hzdr.de/publications/Publ-15908
Publ.-Id: 15908