  Unique superconductivity at surfaces/interfaces, as exemplified by
LaAlO3/SrTiO3 interfaces, and the high transition temperature in ultrathin FeSe
films, have triggered intense debates on how superconductivity is affected in
atomic and electronic reconstructions. The surface of superconducting cubic
spinel oxide LiTi2O4 is another interesting system because its inherent surface
electronic and atomic reconstructions add complexity to superconducting
properties. Investigations of such surfaces are hampered by the lack of single
crystals or high-quality thin films. Here, using low-temperature scanning
tunneling microscopy, we report an unexpected small superconducting energy gap
and a long coherence length on the surface of LiTi2O4 (111) epitaxial thin
films. Furthermore, we find that a pseudogap opening at the Fermi energy
modifies the surface superconductivity. Our results open an avenue, exploring
anomalous superconductivity on the surface of cubic transition-metal oxides
where the electronic states are spontaneously modulated with involving rich
many-body interactions.
