Very-Low-Temperature Resistivity Anomaly inKRb,KNa, andLiMgAlloys

High-precision measurements of the electrical resistivities of $K\mathrm{Rb}$, $K\mathrm{Na}$, and $\mathrm{Li}\mathrm{Mg}$ alloys reveal large anomalous departures from the expected $T^2$ dependence below Å 0.5 K. The dependences of the anomaly in $K\mathrm{Rb}$ upon temperature, residual resistivity, and magnetic field have been studied and, taken together, appear to rule out localization, electron-electron interaction, or Kondo effects as explanations for the anomaly. Two-level-system and charge-density-wave explanations are also considered.