Electronic topological transition in Re1−xMox alloys and its influence on the temperature of the superconducting transition

The features of the variation in the superconducting transition temperature Tc of Re1−xMox alloys in the interval of Mo concentrations C up to 5 at. % (within the solid solution region) are investigated at pressures P of up to 10 kbar. A nonlinear increase of Tc to ≈5 K is observed when an impurity of C≈4.7 at. % Mo is added, and an inflection point is observed at C≈2.35 at. % Mo. The dependence (∂Tc/∂P)(C) has a minimum at the same Mo concentration. This attests to the presence of a critical energy Ecelectronegative relative to Re, lowers the Fermi energy EF0 of Re, and when it crosses the level Ec of the top of the filled d band, which lies below the Fermi energy, an electronic topological transition (ETT) occurs under the influence of the Mo impurity at a concentration C≈2.35 at. %. The minimum and asymmetry of (1/Tc)(∂Tc/∂P)(C) correspond to the appearance of a new hole pocket of the Fermi surface. The d electrons, with a high electronic de...