EPR INVESTIGATION OF SYNTHETIC, DOPED FES2 AND RUS2 SINGLE-CRYSTALS

Synthetic FeS2 and RuS2 single crystals were prepared by the flux meth od using PbCl2, bismut, and tellurium as different solvents. FeS2 and some RuS2 samples were doped with elementary vanadium, other RuS2 crys tals with manganese and nickel. The EPR spectra revealed Mn2+ in the l ow-spin state and Ni2+. The lineshape of the Mn sextet turned out to b e asymmetrical. In some RuS2 samples we detected an isotropic structur eless rather narrow signal with a linewidth down to 0.05 mT and attrib uted it to the conductivity. Its lineshape becomes symmetrical and Lor entzian by grinding the samples to a polycrystalline powder. The EPR p arameters of appropriate spin-Hamiltonians were determined. The intens ities of the allowed and forbidden lines depended very differently on the microwave power due to different degrees of saturation.