Electron-magnon renormalization effects in SrRuO/sub 3/

Summary form only given. In a heavy fermion metal, Fermi liquid theory is thought to hold, with strongly renormalized effective masses for the quasiparticles. The interactions which renormalize the mass also renormalize the scattering rate, however, so that these effects remain unseen to dc conductivity measurements: /spl sigma//sub dc/=ne/sup 2//spl tau/*/m*=ne/sup 2//spl tau//m. While cuprate superconductors represent the most visible challenge to FLT, the superconducting state frequently interferes with our attempts to understand the normal state at low temperatures, where FLT has the most validity.