Charge Ordering and Low-Temperature Lattice Distortion in the {beta}'-(BDT-TTF){sub 2}CF{sub 3}CF{sub 2}SO{sub 3} Dime Mott Insulator.

Journal Article · Wed Jan 29 04:00:00 EST 2020 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.101035150· OSTI ID:1765952

Olejniczak, I.; Wesolowski, R.; Jeschke, H. O.; Valenti, R.; Barszcz, R.; Schlueter, J. A.

We present single-crystal x-ray diffraction measurements, optical investigations, and electronic structure calculations for the organic charge-transfer salt beta'-(BEDT-TTF)(2)CF3CF2SO3 synthesized by electrocrystallization. Electronic structure calculations confirm the quasi-one-dimensional behavior of the compound and optical conductivity measurements reveal the dimer-Mott insulating nature of the system. The splitting of the charge-sensitive nu(2) mode in Raman spectra demonstrates the onset of an interlayer charge-ordered phase below 25 K, also suggested by the crystal structure considerations. This transition is accompanied by clear signatures of a lattice distortion in the BEDT-TTF donor layer, as shown by a splitting of the vibrational nu(3) mode in infrared spectra. At the same time, the sharp redshift of the nu(1) mode involving the BEDT-TTF ethylene groups strongly suggests a significant modification of the hydrogen-type bonding present between the BEDT-TTF donor layer and the CF3CF2SO3- anion layer. These observations point to a subtle interplay of charge and lattice degrees of freedom at the phase transition.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: National Science Foundation (NSF); Deutsche Forschungsgemeinschaft (DFG)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1765952
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 3 Vol. 101; ISSN 2469-9950
• Country of Publication: United States
• Language: English