Full strain tensor of photostriction in classical ferroelectric and multiferroic model systems: light polarization and grain orientation dep

The understanding of the physics behind the photostriction (i.e., lattice distortion under light solicitation) in ferroelectric materials is still hampered by the lack of complete experimental data. Ferroelectrics being non-centrosymmetric materials, the photostriction is expected to behave similarly to the so-called bulk photovoltaic effect (BPVE), despite other mechanisms (e.g., thermal expansion) at play. In this proposal, our objective is to investigate how this strain depends on crystal orientation and light polarization, particularly to identify the characteristic signature of the BPVE. Our approach, we already proven in a previous experiment (HC-4561), is to measure the full strain tensor under the above bandgap illumination by Laue micro-diffraction. We will focus on the model ferroelectric PbTiO3 and multiferroic BiFeO3 systems, available as single crystals and coarse grain ceramics. Scientific background: