The Role Of Oxygen Octahedra Connectivity In Orthorhombic Perovskite Heterostructures

Diplôme Thèse The Role Of Oxygen Octahedra Connectivity In Orthorhombic Perovskite Heterostructures eng 2025-06-17 2025-07-02 author Thibault Clémentine 851519 Services communs de la section de physique (FICO) director Triscone Jean-Marc 21933 Département de physique de la matière quantique (FIMAC) director Gariglio Stefano 0000-0001-8263-4506 508404 Département de physique de la matière quantique (FIMAC) 123 10.13097/archive-ouverte/unige:186391 urn:nbn:ch:unige-1863918 Sc. 5922 This thesis investigates the connectivity of oxygen octahedra in epitaxial heterostructures, showing that their rotational amplitude in thin films can be tuned over a range from a few unit cells to several nanometers by balancing epitaxial strain and octahedral connectivity. Focusing on LaVO₃/DyScO₃, we demonstrate that adjusting growth conditions alters the effective strain on LaVO₃ films. Under compressive strain, both misfit strain and connectivity favor the [110] orientation, while under tensile strain, they compete. Beyond a critical thickness, strain dominates, inducing a shift in preferred orientation to [001], necessitating a structural switching plane. In LaVO₃/(110)GdScO₃, larger tensile strain requires stricter growth control to maintain high crystallinity and avoid defect-related relaxation. Lastly, we explore SrRuO₃/DyScO₃ to tune ferromagnetism via crystal orientation. SrRuO₃ adopts a different orthorhombic symmetry, resolving the strain-connectivity conflict without switching plane; magnetization remains in-plane, with no significant change in magnetic properties detected. Orthorhombic Oxygen Octahedra Epitaxial strain Heterostructures Perovskite Orientation LaVO3 Thin films Pulse Laser Deposition Dewey 500.2 33 Département de physique de la matière quantique 131 false 784 Groupe Triscone efda3c1b-7760-4af4-8003-04a531a3b5e7 Thesis Restricted The_role_of_oxygen_octahedra_connec.pdf 26639560 application/pdf Private 2026-07-11 2a776c69bf32abda39980fb510c9d7739518631cbb46afc691dd86ca23180735 c10f1d90-e0ea-41eb-a2d3-5230f81c7568 Imprimatur Public Numérisation_20250711.jpg 198450 image/jpeg a66c0e2a9668d6e699c34b831605f4074da2128f291b4e6b2880f4e888bc5f97 embargoedAccess Faculté des sciences / Section de physique / Département de physique de la matière quantique

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Thibault, Clémentine

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