Ultrahigh critical magnetic fields superconductors Pb0.9Mo6S7.5

Temperature dependences of magnetic susceptibility, , of single crystals and one-phase polycrystalline ternary molibdenum sulfides with various degree of perfection (where is the electrical resistence, TKis the temperature of transition into the superconducting state) have been studied in the temperature range 4,2-300 K. Materials under study had the following superconducting parameters: , the transition halfwidth for the best samples was kOe/K. It is found that the magnetic susceptibility of investigated samples is paramagnetic and grows temperature decrease and α rise. Strong temperature dependence, χ and the fact that may be accounted for if to assume that the model of electron energy spectrum is valid for ternary molib-denum salfides. According to this model the energy dependence of the density of electron states has the peak near the Fermi level, , and the Fermi level corresponds to that part in the curve where . The band structure, model proposed for ternary molybdenum sulfides to explain our experimental results agrees with the dispersion law which is theoretically developed by O. K. Andersen.