Superconducting transition parameters in aluminum–lithium alloys (0–10 at.% Li)

The superconducting transition temperatures TcTc of face-centered cubic Al1−x–Lix alloys (x=0–0.10x=0–0.10) exhibit a minimum near x=0.03x=0.03 (3 at.% Li). The McMillan strong-coupling TcTc equation yields a similar trend of the electron–phonon coupling constant λλ. Meanwhile, the density of states at the Fermi level N(0)N(0) decreases monotonically with increasing xx. It appears that TcTc drops initially due to a reduced N(0)N(0), which is then overtaken by alloying-enhanced factors of phonon or electron–phonon interaction.