Ferroelectric topology and electronic structure of BaTiO 3 (001)
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Ferroelectric topology and electronic structure of BaTiO 3 (001) 1 Université Paris-Sud 11 – École Doctorale 107 “Physique de la Région Parisienne” 2 Laboratoire d’Étude des Nanostructures et Imagerie de Surface (CEA-Saclay/DSM/IRAMIS/SPCSI) 3 CEA/DAM – Île-de-France 4 Laboratoire Structures, Propriétés et Modélisation des Solides (CNRS-UMR 8580 – École Centrale Paris) Jelle Dionot 1,2 Jointly supervised by Grégory Geneste 3,4 and Nick Barrett 2 1
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Ferroelectric topology and electronic structure of BaTiO 3 (001). Jelle Dionot 1,2. Jointly supervised by Grégory Geneste 3,4 and Nick Barrett 2. 1 Université Paris- Sud 11 – École Doctorale 107 “Physique de la Région Parisienne ” - PowerPoint PPT Presentation
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Ferroelectric topology andelectronic structure of BaTiO3(001)1Universit Paris-Sud 11 cole Doctorale 107 Physique de la Rgion Parisienne2Laboratoire dtude des Nanostructures et Imagerie de Surface (CEA-Saclay/DSM/IRAMIS/SPCSI)3CEA/DAM le-de-France4Laboratoire Structures, Proprits et Modlisation des Solides (CNRS-UMR 8580 cole Centrale Paris)
Jelle Dionot1,2Jointly supervised byGrgory Geneste3,4 and Nick Barrett21OutlineFerroelectric properties of single crystals
Physics and chemistry of surfacesStoichiometryDopingStrain
Experimental and theoretical approachesElectron microscopy and spectroscopyAb initio simulation2
Ferroelectric polarization screening on single crystal------------++++++++-+++++++++++++++++-------------+-+-+-+- - - - - - - +++++++++++++ + + + + Extrinsic (adsorbates)------------Intrinsic(e-h pairs, defects)++--+---+-++---+++---+++Domain orderingBa2+Ti4+O2-3Experimental approach:Surface full-field imaging techniques
500 nm50 nm5 nm
Polarized LightDICOptical microscopyDomain ordering
PEEMPhotoemission thresholdWork function4
LEEMSurface PotentialPhase TransitionMicroscopies (optique, lectrons lents, dlectrons photomis)4Spectromicroscopy in real and reciprocal space (chemistry and band structure)5Real-space imagingWork function variationsSurface charge differences inferroelectric domains
3.2 eV3.5 eV3.3 eV3.4 eVDirect surface chemistryCore level imagingReciprocal-space imaging
Free standing slabs (~130 atoms)Surface Compensation of internal depolarizing fields
2 supercell terminations BaOTiO2
Density Functional Theory based on minimization of total energy of the system at 0 K6Theoretical approach: simulation
Theoretical approach: simulation7++--+---+-++---+++---+++
Out-of-plane polarization with uncompensated depolarizing field
BariumTitaniumOxygenBaO terminationTheoretical approach: simulation8Out-of-plane polarization with uncompensated depolarizing field
BariumTitaniumOxygenTiO2 termination
Experiments & Calculations9ExperimentsCalculationsOxygen vacancies stabilize inward out-of-plane polarization
Surface band structure of doped BaTiO3
PRL 111, 127602 (2013)Strain-polarization coupling
Surface relaxation and rumpling
Thank you for your attention!Jelle Dionot
Pnultime anne de thse
Bt 462, Pe 610So far so good!
ISOE 2013
THANKS!10
