/spl kappa/-(BEDT-TTF)/sub 2/-Cu[N(CN)/sub 2/]Cl: magnet and superconductor. High pressure and high magnetic field experiments

Summary form only given. In this paper, we have surveyed the current status of research having revealed the direct and delicate interplay between superconductivity and magnetism in a 2-d organic crystal [1,2]. The existence of both types of ordering in a wide region of temperatures, external pressures and magnetic fields is firmly established by observations of reentrant superconductivity, and of the high-field induced electron transition from superconducting/metallic to highly-resistive non-metallic state; moreover, the low-temperature ground state at fixed pressure and in zero applied field is found to be either superconducting one or resistive and magnetic-depending on thermal history of a sample or of preceding procedure of magnetic field treatment. Rich phase diagram of the compound, subtle balance between antagonistic states and their interchange via first-order transitions with pronounced temperature and field hysteresis and long time effects, all these signs of unstable electronic structure also suggest that crystal consists of extremely weakly bound molecules. These conclusions are discussed with respect to the possible origin of magnetism in the salt having the highest among organics superconducting T, 13 K.