Antiferromagnetic instability and the metal-insulator transition in $\mathrm{Tm}_{1-x}\mathrm{Yb}_x\mathrm B_{12}$ rare earth dodecaborides

The magnetic and transport characteristics of substitutional solid solutions of the Tm_1−x Yb _x B₁₂ rare earth dodecaborides have been investigated. The measurements performed in the wide temperature range 1.8−300 K on the high-quality single-crystalline samples make it possible to conclude that as x increases, antiferromagnetic instability develops with the quantum critical point (T _N = 0) near x = 0.3 and relevant dielectrization of the electron structure in the range 0 ≤ x ≤ 0.8 takes place. With the results of the thermoelectric measurements in Tm_1−x Yb _x B₁₂, the activation energy values and their dependence on x have been determined.