Localization of Conduction Electrons by Fe, Co, and Ni in1T-TaS2and1

$1T\ensuremath{-}{M}_{x}{\mathrm{Ta}}_{1\ensuremath{-}x}{\mathrm{S}}_{2}$ or $1T\ensuremath{-}{M}_{x}{\mathrm{Ta}}_{1\ensuremath{-}x}{\mathrm{Se}}_{2}$ with $M=\mathrm{F}\mathrm{e},\phantom{\rule{0ex}{0ex}}\mathrm{C}\mathrm{o},\phantom{\rule{0ex}{0ex}}\mathrm{o}\mathrm{r}\phantom{\rule{0ex}{0ex}}\mathrm{N}\mathrm{i}$ shows large increases in resistivity at low temperatures when $\frac{1}{3}>x>~{x}_{c}$ (${x}_{c}\ensuremath{\approx}0.02$ for the disulfides, and 0.15 for the diselenides). We suggest that this increase is due to Anderson localization of the conduction electrons by the random potential of $M$. However, in contrast to the usual impurity state in metals, the presence of a charge-density wave makes this potential temperature dependent and long ranged.