Magnetic Properties of the alloy of κ-(BEDT-TTF)2(1−X)(BEDSe-TTF)2XCu[N(CN)2]Br

In κ-(BEDT-TTF) 2 X, the relationship between the AF-fluctuation and the superconductivity has been discussed by many researchers. In order to investigate the mechanism of the superconductivity in κ-(BEDT-TTF) 2 X, we prepared the alloy of K-(BEDT-TTF) 2(1-X) (BEDSe-TTF) 2X Cu[N(CN) 2 ]Br and measured the magnetic properties of the alloy. The increase of X shifted T c lower and the superconductivity was suppressed over X=0.33. To check the magnetic fluctuation, we also measured the spin-lattice relaxation rate (T 1 T) -1 of the series of the alloy system.