Orientational Enhancement of Surface Phonon Polarity in Superconducting KTaO₃ Interfaces

Orientational Enhancement of Surface Phonon Polarity in Superconducting KTaO₃ Interfaces | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Orientational Enhancement of Surface Phonon Polarity in Superconducting KTaO₃ Interfaces Wei-Tao Liu, Tongying Liu, Jiashi Li, Shiyu Zhang, Tao Zhou, Fanjin Lu, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7875315/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The critical role of symmetry-breaking interfaces in mediating superconductivity has garnered increasing interest in recent years. KTaO 3 (KTO)-based heterointerfaces present a striking example, where the superconducting transition temperature ( T c ) exhibits an intriguing dependence on KTO crystallographic orientation. Here we identify a highly anisotropic surface phonon resonance near 107 meV at KTO and KTO-based heterointerfaces using surface-specific, symmetry-sensitive nonlinear optical spectroscopy. Polarity of this phonon mode scales with crystallographic orientation as (111) >(110) ≫ (001), reaching a 35-fold enhancement over non-superconducting interfaces and tracking the superconducting T c . In addition, a softened local mode near 100 meV is observed and attributed to interfacial oxygen vacancies. Our results provide a framework linking the symmetry-breaking lattice phonons, defects, and anisotropic superconductivity for KTO and related heterointerfaces. Physical sciences/Physics/Condensed-matter physics/Surfaces, interfaces and thin films Physical sciences/Physics/Optical physics/Nonlinear optics Full Text Additional Declarations There is NO Competing Interest. Supplementary Files LAOKTOSFGSupplementaryInfo.docx Supplementary Information Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7875315","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":548905115,"identity":"873bb8e6-2f18-4773-bf45-a7d9841a69fd","order_by":0,"name":"Wei-Tao 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Interfaces","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-7875315/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7875315/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe critical role of symmetry-breaking interfaces in mediating superconductivity has garnered increasing interest in recent years. KTaO\u003csub\u003e3\u003c/sub\u003e (KTO)-based heterointerfaces present a striking example, where the superconducting transition temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e) exhibits an intriguing dependence on KTO crystallographic orientation. Here we identify a highly anisotropic surface phonon resonance near 107 meV at KTO and KTO-based heterointerfaces using surface-specific, symmetry-sensitive nonlinear optical spectroscopy. Polarity of this phonon mode scales with crystallographic orientation as (111) \u0026gt;(110) ≫ (001), reaching a 35-fold enhancement over non-superconducting interfaces and tracking the superconducting \u003cem\u003eT\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e. In addition, a softened local mode near 100 meV is observed and attributed to interfacial oxygen vacancies. Our results provide a framework linking the symmetry-breaking lattice phonons, defects, and anisotropic superconductivity for KTO and related heterointerfaces.\u003c/p\u003e","manuscriptTitle":"Orientational Enhancement of Surface Phonon Polarity in Superconducting KTaO₃ Interfaces","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-25 06:48:12","doi":"10.21203/rs.3.rs-7875315/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-communications","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"NCOMMS","sideBox":"Learn more about [Nature Communications](http://www.nature.com/ncomms/)","snPcode":"","submissionUrl":"https://mts-ncomms.nature.com/","title":"Nature Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Communications","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"64690d8b-df4c-44ae-bb96-de0ee2d48704","owner":[],"postedDate":"November 25th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":58413097,"name":"Physical sciences/Physics/Condensed-matter physics/Surfaces, interfaces and thin films"},{"id":58413098,"name":"Physical sciences/Physics/Optical physics/Nonlinear optics"}],"tags":[],"updatedAt":"2026-04-26T09:25:11+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-25 06:48:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7875315","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7875315","identity":"rs-7875315","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}