Magnetization study of organic superconductor κ-(BEDT-TTF)2Cu(NCS)2

Organic superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) (BEDT-TTF denotes bis(ethylenedithia)tetrathiafulvalene) with T-c similar or equal to 9.5 K has a highly anisotropic nature similar to the high-T-c superconductor. Temperature dependence of magnetization was measured in the field range of 1 kOe less than or equal to H less than or equal to 5 kOe perpendicular to the conducting layers. Near T-c, the reversible magnetization deviates from the mean-field behavior due to the positional distortion of vortices, which is reflected by the crossover of the magnetization curves at T similar or equal to 8.75 K. Far below T-c where the fluctuation is diminished, the magnetization was analyzed using Hao and Clem's model, and the thermodynamic parameters, such as the Ginzburg-Landau parameter kappa, the critical fields [H-c(0) and H-c2(0)] and the characteristic lengths [xi(0) and lambda(0)], were obtained. (C) 2000 Elsevier Science B.V. All rights reserved.