arXiv subjects

Cédric Leuvrey

Publications and source records attributed to Cédric Leuvrey.

3 recordsLinked to original sources

arXiv2026

Strain-driven magnetic anisotropy and spin reorientation in epitaxial Co V 2 O 4 spinel oxide thin films

CoV___O___ (CVO) stands out among spinel vanadates for its ultra-short V-V distances, placing it at the brink of itinerant electron behaviour-an ideal playground for strain engineering. In this work, we exploit this sensitivity by growing high-quality epitaxial CVO thin films on SrTiO___ (001) and MgO (001), inducing compressive and tensile strain, respectively. Using pulsed laser deposition under ultra-low oxygen pressure, we achieve high crystalline quality and straincontrolled tetragonal distortions: c > a under compression (STO) and c < a under tension (MgO). Resonant elastic X-ray scattering confirms a normal spinel structure, with cobalt occupying tetrahedral sites and vanadium octahedral ones. Both strain types reduce charge transport, driving the system into a highly resistive state. Magnetic measurements reveal strain-driven anisotropy switching: STO films transition from out-of-plane to in-plane easy axis below 90 K, while MgO films flip from in-plane to out-of-plane below 45 K. These results highlight CVO's exceptional responsiveness to lattice strain, unlocking a path to finely tunable electronic and magnetic properties. With its strong spin-lattice coupling and potential in spin Hall magnetoresistance, strained CVO emerges as a compelling platform for next-generation lowpower spintronic devices.

cond-mat.mtrl-sci↗

arXiv2023

Room-temperature magnetism and controlled cation distribution in vanadium ferrite thin films

Spinel oxides demonstrate significant technological promise due to the vast array of interrelated physical properties that their unique structure supports. Specifically, the Fe1+xV2-xO4 spinel system garners extensive interest due to the presence of orbitally ordered states and multiferroism. This study focuses on the elaboration of high-quality Fe2VO4 (x = 1) thin films on MgO substrates via pulsed laser deposition. Structural analyses confirm the epitaxial growth of the films, their high crystallinity and fully strained nature. The cationic distribution and stoichiometry were investigated using Resonant Elastic X-ray Scattering experiments, in conjunction with comprehensive characterization of the films' physical and electrical properties. The films exhibit room-temperature magnetism, with a magnetization consistent with the (Fe3+)Td[Fe2+V3+2]OhO4 inverse spinel structure unveiled by anomalous diffraction. This work represents the inaugural successful deposition of Fe2VO4 thin films, thereby expanding the family of spinel vanadium oxide thin films with a new member that demonstrates room-temperature magnetic properties.

cond-mat.mtrl-sci↗

arXiv2022

Unveiling Unconventional Ferroelectric Switching in Multiferroic Ga0.6 Fe1.4O3 Thin Films Through Multiscale Electron Microscopy Investigations

Understanding the polarization switching mechanisms at play in ferroelectric materials is crucial for their exploitation in electronic devices. The conventional centrosymmetric reference structure-based mechanism which accounts for ferroelectricity in most of the usual displacive ferroelectric materials is too energy-demanding for some newly diagnosed ferroelectric materials such as the Ga2-xFexO3 (0.8 < x < 1.4) compounds. Some alternative theoretical propositions have been made and need experimental confirmation. A dual-scale electron microscopy study is performed on thin films of the Ga0.6Fe1.4O3 multiferroic compound. A wide scale precession-assisted electron diffraction tomography study first allows the determination of the structure the compound adopts in thin films, and even permits the refinement of the atomic positions within this structure. Cationic mobility is suggested for two of the atomic positions through the existence of extra electronic density. A local in situ high resolution scanning transmission electron microscopy study then allows confirming these mobilities by directly spotting the cationic displacements on successively acquired images. The whole study confirms an unconventional switching mechanism via local domain wall motion in this compound.

cond-mat.mtrl-sci↗