biostudies-literatureKato TNatural Science Foundation of Beijing MunicipalityCore Research for Evolutional Science and TechnologyUVSORNatural Science Foundation of ChinaGrant-in-Aid for Scientific ResearchJapan Science SocietyJapan Science and Technology Agency (JST), SPRINGNational Natural Science Foundation of ChinaJapan Science and Technology AgencyGP-spin at Tohoku UniveristyJapan Society for the Promotion of ScienceBeijing Natural Science Foundatione2309003https://www.ebi.ac.uk/biostudies/studies/S-EPMC11304331biostudies-literatureUnknown11(29)Applying lattice strain to thin films, a critical factor to tailor their properties such as stabilizing a structural phase unstable at ambient pressure, generally necessitates heteroepitaxial growth to control the lattice mismatch with substrate. Therefore, while homoepitaxy, the growth of thin film on a substrate made of the same material, is a useful method to fabricate high-quality thin films, its application to studying strain-induced structural phases is limited. Contrary to this general belief, here the quasi-homoepitaxial growth of Cs and Rb thin films is reported with substantial in-plane compressive strain. This is achieved by utilizing the alkali-metal layer existing in bulk crystal of kagome metals AV₃Sb₅ (A = Cs and Rb) as a structural template. The angle-resolved photoemission spectroscopy measurements reveal the formation of metallic quantum well states and notable thickness-dependent quasiparticle lifetime. Comparison with density functional theory calculations suggests that the obtained thin films crystalize in the face-centered cubic structure, which is typically stable only under high pressure in bulk crystals. These findings provide a useful approach for synthesizing highly strained thin films by quasi-homoepitaxy, and pave the way for investigating many-body interactions in Fermi liquids with tunable dimensionality.Advanced science (Weinheim, Baden-Wurttemberg, Germany)Quasi-Homoepitaxial Growth of Highly Strained Alkali-Metal Ultrathin Films on Kagome Superconductors.PMC1130433192065109JPMJCR18T123IMS6649Z210006JPMJSP211422IMS6838JP21H04435JP23KJ0099JP23H01115Li YTakahashi TSato TYao YSugawara KTanaka KKato TNakayama KWang ZfalseQuasi-Homoepitaxial Growth of Highly Strained Alkali-Metal Ultrathin Films on Kagome Superconductors.Applying lattice strain to thin films, a critical factor to tailor their properties such as stabilizing a structural phase unstable at ambient pressure, generally necessitates heteroepitaxial growth to control the lattice mismatch with substrate. Therefore, while homoepitaxy, the growth of thin film on a substrate made of the same material, is a useful method to fabricate high-quality thin films, its application to studying strain-induced structural phases is limited. Contrary to this general belief, here the quasi-homoepitaxial growth of Cs and Rb thin films is reported with substantial in-plane compressive strain. This is achieved by utilizing the alkali-metal layer existing in bulk crystal of kagome metals AV₃Sb₅ (A = Cs and Rb) as a structural template. The angle-resolved photoemission spectroscopy measurements reveal the formation of metallic quantum well states and notable thickness-dependent quasiparticle lifetime. Comparison with density functional theory calculations suggests that the obtained thin films crystalize in the face-centered cubic structure, which is typically stable only under high pressure in bulk crystals. These findings provide a useful approach for synthesizing highly strained thin films by quasi-homoepitaxy, and pave the way for investigating many-body interactions in Fermi liquids with tunable dimensionality.2024-01-01T00:00:00Z2024 Aug2025-04-22T21:44:42.057Z2025-04-06T03:45:29.485ZS-EPMC113043313882876410.1002/advs.202309003