T{sub c}-dependent Raman scattering from a high-frequency phonon in {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br
- Physics Department, University of British Columbia, Vancouver, British Columbia, V6T1Z1 (CANADA)
- Chemistry and Materials Science Divisions, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
We report the temperature dependence of the frequencies of two high-frequency intramolecular modes in {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br measured by resonant Raman scattering, with the use of a Fourier-transform spectrometer equipped with an infrared laser. One of these modes, that at 892cm{sup {minus}1} and assigned to {nu}{sub 60}(B{sub 3g}) exhibits an increase below T{sub c} of 2.2{plus_minus}0.7cm{sup {minus}1} and 2.2{plus_minus}0.4cm{sup {minus}1} when measured in a Janis Dewar and in a Heli-Tran refrigerator, respectively. A smaller increase is observed in the deuterated sample and no increase is observed at all if the samples are cooled too rapidly. Two other modes, {nu}{sub 3}(A{sub g}) at 1474cm{sup {minus}1} and {nu}{sub 9}(A{sub g}) at 503cm{sup {minus}1}, show no such increase below T{sub c} in the slowly cooled samples. We speculate that the normal electron-phonon interaction may not be responsible for the frequency increase but that the superconducting transition may involve a change in either the geometry or the arrangement of the BEDT-TTF molecules to which the particular mode is sensitive. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 573797
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 1 Vol. 57; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
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