PHYSICAL-PROPERTIES OF SOME ET-BASED ORGANIC METALS AND SUPERCONDUCTORS WITH MERCURY CONTAINING ANIONS

Because of mercury atoms capability of forming the compounds with vari ous coordination, the application of the electrolytes with Hg containi ng anions in electrochemical oxidation of ET (bis(ethylenedithio)tetra thiafulvalene) results in the formation of ET salts with the anions of different composition. The properties of organic metals and supercond uctors are briefly described for three families: 1) ET(4)Hg(3-delta)X( 8) ((delta < 0.3, X = Cl, Br, I) 2) (ET)(2)[Hg(SCN)(3-n)X(n)] (X = F, Br, I for n = 1; X = Cl for n = 1, 2), 3) (ET)(8)[Hg(4)X(12)(C6H5Y)] ( X,Y = Cl, Br). The superconductivity of (ET)(2)[Hg(SCN)Cl-2] under pre ssure about 9 kbar with T-onset = 2 K is reported for the first time. The coexistence of two incommensurate sublattices in the salts of (ET) (4)Hg(3-delta)X(8) family probably gives rise to their unusual physica l properties such as an abnormally high anisotropy of conductivity tog ether with its growth with temperature drop, a positive curvature of t he upper critical magnetic held, H-c2, and an exceeding of Clogston pa ramagnetic limit, the invalidity of Korringa law for the temperature d ependence of spin-lattice relaxation rate, the growth of the temperatu re of a superconducting transition T-c with pressure, dT(c)/dp > 0, an d a series of other peculiarities. Shubnikov-de Haas oscillations were observed for some salts of (ET)(8)[Hg(4)X(12)(C6H5Y)(2)] family. The possible types of Fermi surface are discussed for these salts.