Superconductivity and charge-density waves in Ta- and Ti-doped NbSe3

Abstract

We have measured the resistance and critical fields of a series of alloys of Ti and Ta substituted for Nb in Nb${\mathrm{Se}}_3$. For concentrations of 5 at.% Ta and 0.1 at.% Ti we find that the charge-density-wave transitions are greatly smeared or suppressed and that the alloys become bulk anisotropic superconductors. Our results are discussed in terms of the competition between the charge-density waves and superconductivity for states at the Fermi surface.