Isotope Effect on Physical Properties of BEDT-TTF Based Organic Superconductors

Abstract
The isotope shifts of the superconducting transition temperature for K-(BEDT-TTF)2Cu[N(CN)2]Br were evaluated from the resistivity and dc magnetization measurements. The deuteration of the terminal ethylene groups of the donor molecule lowered Tc by 0.4 to 0.5K, whereas the 13C substitution on the same fragments gave no isotope shifts within the experimental accuracy.