Superconductivity of {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br: Isotope effect revisited[bis(ethylenedithio)tetrathiafulvalene]
In 1991, the authors reported a normal isotope effect in organic superconductor {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br, when all the hydrogen atoms of BEDT-TTF were replaced with deuterium. In other words, T{sub c} was depressed by as much as 0.9 K, in contrast to the inverse isotope effect commonly observed in 10K-class organic superconductors. Recently, it was reported that the deuterated {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br shows an insulating nature when cooled very rapidly. Therefore, it is necessary for us to reexamine the superconducting transition of both deuterated and undeuterated {kappa}-(BEDT-TTF){sub 2}Cu[N(CN){sub 2}]Br by SQUID measurements with special attention to the cooling speed. The authors studied the effect of cooling rate ranging from 10K/min down to as slow as 0.02 K/min, and observed a significant effect not only on the superconducting transition temperature T{sub c} but also on the superconducting volume fraction.
- Research Organization:
- Electrotechnical Lab., Tsukuba, Ibaraki (JP)
- OSTI ID:
- 20034172
- Country of Publication:
- United States
- Language:
- English
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