Optical Properties of Two-Dimensional Organic Conductors: Signatures of Charge Ordering and Correlation Effects

Power-law dependence of the optical conductivity observed in the quantum spin-liquid compoundκ-(BEDT-TTF)2Cu2(CN)Elsässer1, Wu2, Dressel3 et al. 2012Phys. Rev. BSelf Cite

“…Temperature dependent optical reflection experiments R(ν, T ) were performed in a wide frequency range using several Fourier transform infrared spectrometers (23−12 000 cm −1 ) with an infrared microscope attached to it; 25,26 in addition the high-frequency optical properties (up to 35 000 cm −1 ) were determined by spectroscopic ellipsometry at room temperature. For T < 100 K the optical transmission was measured in the THz range (18 − 46 cm −1 ) using a coherent source spectrometer.…”

“…2 and 3, the spectra of κ-CN and κ-Cl are rich in vibrational excitations. Most of them are due to internal vibrations of the BEDT-TTF molecules, with many of them excited via electronmolecular vibrational (emv) coupling 25 which results in asymmetric Fano resonances. They are best taken into account by the cluster model (see for example Rice 37 and Delhaes and Yartsev 38 ) that describes the optical properties of molecular clusters with arbitrary geometry and equilibrium charge density distribution.…”

Metal-insulator transition in the dimerized organic conductor κ−(BEDT-TTF)2Hg(SCN)2Br

“…The out-of-phase molecular vibrations of the two C=C bonds of the inner rings provide a powerful and well-established method to identify the amount of charge on molecular lattice sites. 27,29,31 The frequency dependence of the ν 27 (b 1u ) mode allows for a quantitative determination of the charge per BEDT-TTF molecule and thus the most accurate way to monitor the temperature-dependence of the charge disproportion- ation. The resulting conductivity spectra in the region of the ν 27 (b 1u ) mode are presented in Fig.…”

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

“…Stimulated by the experimental findings of CO, theoretical studies were conducted on the role of intersite Coulomb interaction in CO [16][17][18], lattice distortion accompanied by CO [19][20][21], the relationship between CO fluctuation and superconductivity (SC) [22], and quantum criticality at the edge of CO [23]. Subsequently, several experimental and theoretical studies have been conducted [24][25][26][27]. Some of these will be introduced from Section 3 on, in relation to the experimental results.…”