Superconductivity in Cubic La₃Al with Interstitial Anionic Electrons

We observed superconductivity in a cubic La_3Al single crystal that exhibits metallic behavior in the normal state without an observable structural transition and enters the superconducting state below T_\rm c\sim6.32 K. Detailed characterization and analysis indicate that cubic La_3Al 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 La_3Al can be considered as a novel electride superconductor.