Inferior Interfacial Superconductivity in 1 UC FeSe/SrVO₃/SrTiO₃ with Screened Interfacial Electron–Phonon Coupling

Monolayer FeSe/TiO x and FeSe/FeO x interfaces exhibit significant superconductivity enhancement compared to bulk FeSe, with interfacial electron-phonon coupling (EPC) playing a crucial role.However, the reduced dimensionality in monolayer FeSe, which may drive superconducting fluctuations, complicates the understanding of the enhancement mechanisms.Here we construct a new superconducting interface: monolayer FeSe/SrVO 3 /SrTiO 3 , in which the itinerant electrons of highly metallic SrVO 3 films can screen all the high-energy Fuchs-Kliewer phonons, including those of SrTiO 3 , making it the first FeSe/oxide system with screened interfacial EPC while maintaining the monolayer FeSe thickness.Despite comparable doping levels, the heavily electron-doped monolayer FeSe/SrVO 3 exhibits a lower pairing temperature (T g ∼ 48 K) than FeSe/SrTiO 3 and FeSe/LaFeO 3 .Our findings disentangle the contributions of interfacial EPC from dimensionality on enhancing T g in FeSe/oxide interfaces, underscoring the importance of interfacial EPC in T g enhancement.This FeSe/VO x interface also provides a platform for studying the interfacial superconductivity.