Bandwidth-controlled Mott transition in $\kappa -(BEDT-TTF{)}_{2}Cu[N(CN{)}_2]B{r}_{x}C{l}_{1-x}$ I. Optical studies of localized charge excitations

Abstract

Infrared reflection measurements of the half-filled two-dimensional organic conductors $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]Br${}_x$Cl${}_{1-x}$ were performed as a function of temperature ($5\mathrm{K}<T<300$ K) and Br-substitution ($x=0$, 40%, 73%, 85%, and 90%) in order to study the metal-insulator transition. We can distinguish absorption processes due to itinerant and localized charge carriers. The broad mid-infrared absorption has two contributions: transitions between the two Hubbard bands and intradimer excitations from the charges localized on the (BEDT-TTF)${}_2$ dimer. Since the latter couple to intramolecular vibrations of BEDT-TTF, the analysis of both electronic and vibrational features provides a tool to disentangle these contributions and to follow their temperature and electronic-correlations dependence. Calculations based on the cluster model support our interpretation.

12 pages, 12 figures

References in corpus (1)

• Electronic correlation in the infrared optical properties of the quasi two dimensional $\kappa$-type BEDT-TTF dimer system

Cited by in corpus (4)

• Bandwidth-controlled Mott transition in kappa-(BEDT-TTF)2Cu[N(CN)2]Br{x}Cl{1-x}: Optical studies of correlated carriers
• Quasiparticles at the verge of localization near the Mott metal-insulator transition in a two-dimensional material
• Optical probe of carrier doping by X-ray irradiation in organic dimer Mott insulator $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2]$Cl
• DC and high-frequency conductivity of the organic metals beta"-(BEDT-TTF)2SF5RSO3 (R = CH2CF2 and CHF)