MAGNETIC PENETRATION DEPTH IN THE CHEVREL-PHASE SUPERCONDUCTORS SNMO6S8-XSEX AND PBMO6S8-XSEX

A full account of positive-muon spin-rotation (mu+SR) studies on the s ystematics of the magnetic penetration depth lambda in the isotropic C hevrel-phase superconductors SnMo6S8-xSex (x=0,1,4,7) and PbMo6S8-xSex (x=0,4) is presented. The absolute determination of lambda from the m uSR data necessitates a careful analysis of the muSR line shape and a comparison with simulated data, taking into account distortions of the flux-line lattice and a distribution of demagnetization factors in th e sintered granular polycrystalline probes investigated. A correlation between T(c) and 1/lambda2 iS found which supports a recently develop ed quantum percolation model.