Electronic properties of organic conductors /spl kappa/- (BEDT - TTF)/sub 2/Cu(N(CN)/sub 2/]X (X=Br,I) as revealed by ESR

Summary form only given. The results of the conduction electron spin resonance (CESR) study of quasi two dimemsional organic charge transfer salts /spl kappa/- (BEDT - TTF)/sub 2/Cu(N(CN)/sub 2/]X (X=Br and I) are reported. The CESR experiments were performed at 9.3GHz within a temperature interval 7.5-300K. The angular and temperature dependencies of the CESR line parameters (intensity, width and g-factor) have been examined. The data witness for a complicated electronic structure of these compounds which probably can be treated as semimetals with a narrow gap or pseudogap in the electronic density of states near the Fermi level. It was concluded that both spin relaxation and momentum relaxation may be determined by a scattering of conduction electrons on the vibrations of the ethylene end groups of the BEDT-TTF molecule. The absence of strong correlation between the observed spin orbit anisotropy and of the spin relaxation anisotropy feasibly points for anisotropy also of the electron-phonon interaction.