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PEEM imaging of ferroelectric domain walls under in-situ mechanical stress

Contact: BARRETT Nick, , nick.barrett@cea.fr, +33 1 69 08 32 72
The aim of the internship is to carry out in-situ studies of the electro-mechanical coupling using photoemission electron microscope (PEEM) imaging of domain walls at the surface of BaTiO3.
Possibility of continuation in PhD: Oui
Deadline for application:30/01/2019

Full description:
In ferroic materials domain walls (DWs) separate domains with different order parameters. Domain wall engineering in ferroic materials is one possible route where the DW rather than the bulk material becomes the active element. The challenge then is to predict and control the nanoscale DW functionality [1].
In BaTiO3 the ferroelectric polarizations of adjacent domains can be oriented at 90° or 180° with respect to one another. In the case of 90° orientation the domain wall is also ferroelastic, separating domains under different mechanical strain. This allows envisaging electro-mechanical coupling between applied mechanical stress and the ferroelectric response of the material.
Our aim is to carry out in-situ studies of the electro-mechanical coupling using photoemission electron microscope (PEEM) imaging [2] of DWs at the surface of BaTiO3.
A micro-engineered system for the application of mechanical stress will be used to control the density and structure of the domains and DWs in single crystal ferroelectric and ferroelastic materials, principally BaTiO3.
The internship requires initial characterization in the laboratory the performance of the system for applying stress. Domain ordering and DWs will be imaged using optical microscopy. Then, the micro-mechanical system will be mounted in the PEEM analysis chamber under ultra-high vacuum (10-10 mbar) and first complementary measurements carried out to validate the experimental set-up.

[1] G. Catalan, J. Seidel, R. Ramesh, Rev. Mod. Phys. 84, 119 (2012)
[2] Full field electron spectromicroscopy applied to ferroelectric materials
N. Barrett, J. E. Rault, J. L. Wang, C. Mathieu, A. Locatelli, T. O. Mentes, M. A. Niño, S. Fusil, M. Bibes, A. Barthélémy, D. Sando, W. Ren, S. Prosandeev, L. Bellaiche, B. Vilquin, A. Petraru, I. P. Krug and C. M. Schneider, J. Appl. Phys. 113, 187217 (2013).
Technics/methods used during the internship:
Optical microscopy Photoemission electron microscopy Low energy electron diffraction

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