The effects of hydrogen impurities on charge-density waves (CDW’s) in ${\mathrm{NbSe}}_3$ have been investigated. Hydrogen can be introduced interstitially into ${\mathrm{NbSe}}_3$ in concentrations of at least several atomic percent with no effects on the crystal structure and only weak effects on the Peierls transitions. The threshold electric field $E_T$ for charge-density-wave depinning and the inverse of the residual resistivity ratio $r_R^{\mathrm{-}1}$ increase monotonically with H concentration for small concentrations. For concentrations above 1.5 at. %, $E_T$ and $r_R^{\mathrm{-}1}$ exhibit a plateau, which we interpret as evidence for H clustering or ordering. Several different measurements indicate that CDW interaction with H is roughly 100 times smaller than with Ta, the most weakly perturbing substitutional impurity in ${\mathrm{NbSe}}_3$. Hydrogen doping should thus allow study of CDW’s in a new, very weakly pinned regime. In nominally pure ${\mathrm{NbSe}}_3$ prepared by standard methods, H is present in larger quantities than any other impurity, and may play an important role in memory effects and long-time-scale fluctuation phenomena.

• Received 26 June 1989

DOI:https://doi.org/10.1103/PhysRevB.40.4205