Dresden 2026 – scientific programme
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FM: Fachverband Funktionsmaterialien
FM 4: Focus Session: (Anti)ferroic states – Non-conventional states I
FM 4.7: Talk
Monday, March 9, 2026, 17:00–17:15, BEY/0138
Optical control of ferroelectric polarization in epitaxial lead titanate thin films — •Valentine Gillioz, Manfred Fiebig, and Morgan Trassin — ETH Zurich, Switzerland
In this work, we use light as an active tool for remotely and dynamically controlling ferroelectricity in epitaxial PbTiO3-based thin films and heterostructures. The exposure to above-bandgap ultraviolet (UV) light enables the manipulation of charge-screening dynamics via the accumulation of photo-induced charge carriers at the bottom electrode/ferroelectric Schottky interface. A transient light-induced enhancement (or suppression) of spontaneous polarization is observed using second-harmonic generation (SHG) in films with a pristine upward (or downward)-oriented polarization. Here, we explore the impact of PbTiO3 growth conditions on the photoresponse of the films in more depth. Importantly, we show a robust and improved cyclability of the optical modulation of the ferroelectric polarization in films grown at low oxygen partial pressure (∼ 10−2mbar) pointing to the role of oxygen vacancies in the light-induced polarization change. In addition, we combine our ability to monitor the polarization dynamics during the thin-film growth process using in-situ SHG with the UV light exposure to balance the depolarizing-field contribution and the light-induced polarizing effect in our heterostructures. We report a strong on/off ratio in the optical manipulation of ferroelectric polarization between a fully depolarized state in dark conditions and a polarized state under UV light exposure. Our work, hence, constitutes a critical step towards all-optical control of ferroelectricity in functional thin films.
Keywords: lead titanate; optical control