Reasons for Tsub(k) change in Al-doped V3Ge

Thermal capacity (2-800 K) and magnetic susceptibility (from Tsub(k) up to 300 K) of V3Ge and Vsub(3)Gesub(0.88)Alsub(0.12) systems are measured. Joint analysis of the obtained and literature data on inelastic neutron scattering allowed to calculate the phonon thermal capacity and its anharmonic component, the temperature dependence of the electronic thermal capacity coefficient, the zone density of states on the Fermi level and parameter of the electron-phonon interaction. Almost twice increase of Tsub(k) at substitution of 12 at.% germanium by aluminium is mainly explained by the increase of the density of electron states on the Fermi level. Slight softening of the phonon spectra also leads to the growth of Tsub(k), but its contribution is considerably smaller