Divergence of the Very-Low-Temperature Residual Resistivity ofTmxSeasx→1

Abstract

The resistivity of the intermediate-valence compounds ${\mathrm{Tm}}_x\mathrm{Se}$ ($0.79<x<\mathrm{}0.993\mathrm{}$) has been measured down to 10 mK. The variation of the residual resistivity with composition (i.e., with the proportion of ${\mathrm{Tm}}^{2+}$) suggests that a perfectly stoichiometric system might become insulating at 0 K. This divergence seems to take place when the two valence states are equal in concentration. A possible interpretation based on the recent developments of the Kondo-lattice models is discussed.