doi:10.3390/nano12071232engBarriuso, E.Koutsogiannis, P.Serrate, D.Herrero-Martín, J.Jiménez, R.Magén, C.Algueró, M.Algarabel, P. A.Pardo, J. A.Direct epitaxial growth of polar Hf0.5 Zr0.5 O2 films on corundumART-2022-128325Single-phase epitaxial Hf0.5 Zr0.5 O2 films with non-centrosymmetric orthorhombic structure have been grown directly on electrode-free corundum (a-Al2 O3) substrates by pulsed laser deposition. A combination of high-resolution X-ray diffraction and X-ray absorption spectroscopy confirms the epitaxial growth of high-quality films belonging to the Pca21 space group, with 111] out-of-plane orientation. The surface of a 7-nm-thick sample exhibits an atomic step-terrace structure with a corrugation of the order of one atomic layer, as proved by atomic force microscopy. Scanning transmission electron microscopy reveals that it consists of grains with around 10 nm lateral size. The polar nature of this film has been corroborated by pyroelectric measurements. These results shed light on the mechanisms of the epitaxial stabilization of the ferroelectric phase of hafnia. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.2022http://zaguan.unizar.es/record/11733010.3390/nano12071232http://zaguan.unizar.es/record/117330oai:zaguan.unizar.es:117330info:eu-repo/grantAgreement/ES/AEI/PID2019-107338RB-C64info:eu-repo/grantAgreement/ES/DGA/E28-20Rinfo:eu-repo/grantAgreement/ES/DGA-FSE/E12-20Rinfo:eu-repo/grantAgreement/EC/H2020/ 861153/EU/Materials for Neuromorphic Circuits/MANICThis project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 861153-MANICinfo:eu-repo/grantAgreement/EC/H2020/823717/EU/Enabling Science and Technology through European Electron Microscopy/ESTEEM3This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 823717-ESTEEM3info:eu-repo/grantAgreement/ES/MCIU/PID2020-112914RB-I00info:eu-repo/grantAgreement/ES/MCIN/AEI/10.13039/501100011033info:eu-repo/grantAgreement/ES/MICINN/MAT2017-88788-RNanomaterials 12, 7 (2022), 1232 [11 pp]byhttp://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccess