Inferior Interfacial Superconductivity in 1 UC FeSe/SrVO<sub>3</sub>/SrTiO<sub>3</sub> with Screened Interfacial Electron-Phonon Coupling.
basic_science · Level V
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- Record sourced from PubMed, PMID 38967395.
- Also identified by DOI 10.1021/acs.nanolett.4c01612.
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Abstract
Single-unit cell (1 UC) FeSe interfaced with TiO<sub><i>x</i></sub> or FeO<sub><i>x</i></sub> exhibits significantly enhanced superconductivity compared to that of bulk FeSe, with interfacial electron-phonon coupling (EPC) playing a crucial role. However, the reduced dimensionality in 1 UC FeSe, which may drive superconducting fluctuations, complicates our understanding of the enhancement mechanisms. We construct a new superconducting interface, 1 UC FeSe/SrVO<sub>3</sub>/SrTiO<sub>3</sub>. Here, the itinerant electrons of highly metallic SrVO<sub>3</sub> films can screen all high-energy Fuchs-Kliewer phonons, including those of SrTiO<sub>3</sub>, making it the first FeSe/oxide system with screened interfacial EPC while maintaining the 1 UC FeSe thickness. Despite comparable doping levels, the heavily electron-doped 1 UC FeSe/SrVO<sub>3</sub> exhibits a pairing temperature (<i>T</i><sub>g</sub> ∼ 48 K) lower than those of FeSe/SrTiO<sub>3</sub> and FeSe/LaFeO<sub>3</sub>. Our findings disentangle the contributions of interfacial EPC from dimensionality in terms of enhancing <i>T</i><sub>g</sub> in FeSe/oxide interfaces, underscoring the critical importance of interfacial EPC. This FeSe/VO<sub><i>x</i></sub> interface also provides a platform for studying interfacial superconductivity.