Uniaxial-strain dependence of shear-modulus anomalies inTaS3

We have measured the changes in shear modulus and internal friction in ${\mathrm{TaS}}_3$ when the charge-density wave (CDW) becomes depinned, as a function of uniaxial strain (ε), and compared the results with the strain dependence of transport properties. For strains above a critical strain ${\mathrm{\epsilon }}_{\mathit{c}}$≃0.5%, where the normal conductivity is a maximum and CDW conductivity a minimum, a second depinning threshold appears, and the elastic anomalies decrease by an order of magnitude. Unlike the case for the conductivity, the low-strain elastic anomalies are not restored by further increases in strain. The results are interpreted in terms of the interaction of a soliton lattice with the CDW.