Localized magnetic moments on chromium and manganese dopant atoms in niobium and vanadium

Abstract

We have made magnetic susceptibility measurements on films of Nb and V, pure and doped with Cr and Mn. The results indicate the presence of localized moments on Cr and Mn dopant atoms in both Nb and V. We discuss the data in terms of a model which takes the magnetic behavior of the host metals into account. We have also measured the superconducting transition temperature, $T_c$, and the upper critical magnetic field, $H_{c2}$(T), of several Nb films, pure and doped with Cr and Mn. We find that $T_c$ of Nb is decreased in the presence of Cr or Mn, by amounts that are consistent with the existence of localized moments. The results for $H_{c2}$(T) indicate, for both Cr and Mn dopants in Nb, that the pair-breaking effect of the magnetic dopants is additive with that of the applied magnetic field.