Superconductivity in Cubic La₃Al with Interstitial Anionic Electrons

We observed superconductivity in a cubic La₃Al single crystal that exhibits metallic behavior in the normal state without an observable structural transition and enters the superconducting state below T_c ~ 6.32 K. Detailed characterization and analysis indicate that cubic La₃Al is a bulk type-II BCS superconductor. Moreover, theoretical calculations show that it can host interstitial anionic electrons located at the body center of the cubic unit cell, which confirms electron–phonon coupling as the superconducting mechanism. Therefore, cubic La₃Al can be considered as a novel electride superconductor.