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Isotope effect in {sup 13}C-substituted (central C=C) {kappa}-phase organic superconductors

Conference ·
OSTI ID:10180356
The organic electron-donor molecule ET [bis(ethylenedithio)tetrathiafulvalene] was synthesized twice by the identical route: (a) with natural ({sup 12}C) carbon isotopic distribution; (b) with 95% {sup 13}C, in the central C=C double bond position. The superconducting transition temperatures (in magnetic fields of 0.0--0.4 T) of single crystals prepared by both routes of ET synthesis were found, by the use of ac susceptibility measurements, to be identical within the precision of the measurements ({approximately}O.lK or 1%) for the ambient-pressure superconductors {kappa}(ET){sub 2}Cu(NCS){sub 2} and {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br. The absence of an effect of such isotopic replacement on Tc indicates that the central C=C stretching vibration (a high-energy optical mode at {approximately}1500 cm{sup {minus}1}) is not the dominant contributor to the superconducting pairing mechanism in these systems.
Research Organization:
Argonne National Lab., IL (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
10180356
Report Number(s):
ANL/CP--76908; CONF-9208132--2; ON: DE92040748
Country of Publication:
United States
Language:
English