High temperature superconductivity at FeSe/LaFeO₃ interface

Enormous enhancement of superconducting pairing temperature (T_g) to 65 K in FeSe/SrTiO₃ has made it a spotlight. Despite the effort of interfacial engineering, FeSe interfaced with TiO_x remains the unique case in hosting high T_g, hindering a decisive understanding on the general mechanism and ways to further improving T_g. Here we constructed a new high-T_g interface, single-layer FeSe interfaced with FeO_x-terminated LaFeO₃. Large superconducting gap and diamagnetic response evidence that the superconducting pairing can emerge near 80 K, highest amongst all-known interfacial superconductors. Combining various techniques, we reveal interfacial charge transfer and strong interfacial electron-phonon coupling (EPC) in FeSe/LaFeO₃, showing that the cooperative pairing mechanism works beyond FeSe-TiO_x. Intriguingly, the stronger interfacial EPC than that in FeSe/SrTiO₃ is likely induced by the stronger interfacial bonding in FeSe/LaFeO₃, and can explain the higher T_g according to recent theoretical calculations, pointing out a workable route in designing new interfaces to achieve higher T_g.