{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"eacc46044711332f81c388c846fc8580729e0f91204372d0df8f98524a285f75","created":"2026-10-03T07:17:59Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"c66fb408fa9e55c200cdf11047f6b591788de0c2202063b4dbf1cd61fdd8091e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"cm.ferroelectric-polar-textures.hfo2-ferroelectricity","kind":"phenomenon","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Hafnium oxide, already used in computer chips, turned out in 2011 to be ferroelectric when made as films a few dozen atoms thick, although its bulk crystal is not. Why the polar crystal phase survives and why the response grows with repeated switching, called wake-up, are open.","posed_since":"2011","precise":"Doped (Si, Zr, La, Y) HfO2 films of thickness about 5e-7 to 2e-6 cm show remanent polarization of order $3\\mathrm{e}4 \\text{ to } 9\\mathrm{e}4\\,\\mathrm{statC}/\\mathrm{cm}^{2}$, attributed mainly to the metastable orthorhombic $\\mathrm{Pca2}_{1}$ phase. Determine which factors stabilize it (surface and grain-boundary energy, dopants, oxygen vacancies, stress, electrodes), whether other polar phases contribute, and the mechanism of wake-up and fatigue (oxygen-vacancy redistribution versus field-induced transformation from tetragonal or monoclinic grains). An answer is a phase-stability and switching model predicting remanent polarization versus thickness, dopant and cycle number.","problem_ref":null,"references":"","settled_by":"In situ structural imaging of individual grains through wake-up cycling, matched by a first-principles phase-stability model that predicts the measured polarization.","status_note":"The orthorhombic $\\mathrm{Pca2}_{1}$ phase is widely accepted as the main polar phase; its stabilization route and the wake-up mechanism remained debated as of 2025.","title":"What stabilizes ferroelectricity and wake-up in thin-film HfO2","topic_ref":"39675ee993fdae1601831aaa7eb336e8100565a08d8679ad19287c2eb2abba01"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"088cb2595511506ca5cc1cb2ab67f7a59b54da87f26420aa278e9be699eabd0a","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"4f19f2b129c9bc85eeb8d5764935cc40d12be438caaa1d5ca9fa23a740521c75","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"p2HwXVHWiGw-qroBq9wF6UlXaEUCN4mDPr63cYDO33tgeaUpLlpcex-v1OIqfr0QrVij644CZt4ACsdvuapEAw"},"schema":"pubphys.envelope/1"},"record_hash":"088cb2595511506ca5cc1cb2ab67f7a59b54da87f26420aa278e9be699eabd0a","leaf_index":980}