Raman studies of BEDT-TTF molecule-based organic superconductors
The temperature dependence of the frequencies of the Raman features due to {nu}{sub 9} (A{sub g}) and {nu}{sub 60} (B{sub 3g}) modes has been measured in the BEDT-TTF (ET) molecule-based organic superconductors {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br, {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl, {alpha}{sub t}-(ET){sub 2}I{sub 3}, and {beta}-(ET){sub 2}AuI{sub 2}. The frequency of the {nu}{sub 9} (A{sub g}) mode was observed to soften in {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br and {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Cl at low temperatures where NMR data indicated antiferromagnetic fluctuations, providing evidence of spin-phonon interactions. The result is also compared with a very recent theory which deals with the effect of electronic correlations on the frequencies of the molecular phonon modes. We observed a peak splitting for the {nu}{sub 60} (B{sub 3g}) mode in {alpha}{sub t}-(ET){sub 2}I{sub 3} below 190 K, where an incommensurate superstructure was reported, and a frequency decrease of 1.7{+-}0.4 cm{sup -1} for the upper component of the {nu}{sub 60} (B{sub 3g}) mode in the superconducting compound, demonstrating further the unusual properties of this mode.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 40276994
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 2 Vol. 64; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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