High temperature superconductivity at FeSe/LaFeO3 interface

Enormous enhancement of superconducting pairing temperature ( T g ) to 65 K in FeSe/SrTiO 3 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 LaFeO 3 . 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/LaFeO 3 , showing that the cooperative pairing mechanism works beyond FeSe-TiO x . Intriguingly, the stronger interfacial EPC than that in FeSe/SrTiO 3 is likely induced by the stronger interfacial bonding in FeSe/LaFeO 3 , 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 . An enhanced superconducting pairing temperature ( T g ) has only been observed in single-layer FeSe interfaced with TiO x system. Here, the authors construct a new interface composed of single-layer FeSe interfaced with LaFeO 3 showing a highest T g of 80 K among all-known interfacial superconductors.