Scanning tunneling spectroscopy of superconductivity on surfaces of LiTi2O4(111) thin films

Abstract

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.

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Cited by in corpus (11)

• Tailoring Magnetism in Self-intercalated Cr1+δTe2 Epitaxial Films
• Evidence for unconventional superconductivity in a spinel oxide
• Evidence of a distinct collective mode in Kagome superconductors
• Anomalies of upper critical field in the spinel superconductor LiTi${}_2$O${}_{4-\delta }$
• Ionic liquid gating induced two superconductor-insulator phase transitions in spinel oxide Li${}_{1\pm x}$Ti${}_2$O${}_{4-\delta }$
• Intrinsic finite-energy Cooper pairing in $j=3/2$ superconductors
• Epitaxial stabilization of an orthorhombic Mg-Ti-O superconductor
• Epitaxial growth and scanning tunneling microscopy of LiV${}_2$O${}_4$ thin films on SrTiO${}_3$(111)
• Evolution of orbital excitations from insulating to superconducting MgTi${}_2$O${}_4$ films
• Surface-phase superconductivity in Mg-deficient V-doped MgTi${}_2$O${}_4$ spinel
• Exploring the Electronic Nature of Spinel Oxides: A Review of Their Electron Interactions and Prospects