Physical properties and superconductivity in the cubic A15-type Ta3Ge compound: A first principles study

In this theoretical study, we have targeted to present the characteristic features of the superconductivity in the cubic A15-type compound Ta3Ge by investigating its structural, electronic, elastic, mechanical, phonon, and electron–phonon interaction properties in detail. A critical examination of elastic moduli of Ta3Ge reveals that it is soft (ductile) due to significant metallic bonding. A critical surveying of electronic density of states reveals that Ge electronic states make negligible additive to the main valence band region of Ta3Ge while its transition metal d states dominate this region. An examination of our phonon results indicate that the low-frequency optical phonon branches and three acoustic phonon branches of Ta3Ge are mainly dominated by the vibrations of Ta atoms. Thereby, their d states and their vibrations become the main actors of the transition from the normal state to the superconducting state for Ta3Ge. From the integration of the Eliashberg spectral function of Ta3Ge, the values of average electron–phonon coupling parameter and logarithmically averaged phonon frequency are found to be 1.08 and 123.05 K, respectively, producing its superconducting temperature Tc = 8.3 K, being in good accordance with the experimental value of 8.0 K.