Berlin 2024 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 5: Thin oxides and oxide layers (joint session DS/KFM)

KFM 5.8: Vortrag

Montag, 18. März 2024, 11:30–11:45, A 053

Ferroelectric polarization rotation through He irradiation induced uniaxial strain — •Andreas Herklotz¹, Robert Roth¹, Kathrin Dörr¹, Alessandro Mazza², and Thomas Zac Ward³ — ¹1) Institute for Physics, Martin-Luther-University Halle-Wittenberg, Halle, Germany — ²2) Los Alamos National Laboratory, Los Alamos, USA — ³3) Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, USA

The physical properties of ferroic thin films are typically dominated by their domain configurations and their responses to external fields. A central prerequisite to domain engineering and harnessing functionalities of ferroelectric thin films is thus the control of the polarization orientation. Historically, the symmetry of ferroelectric films has been mainly tailored by heteroepitaxial in-plane strain or a variation of growth conditions inducing defects.

Here, we deploy low-energy He implantation as an alternative approach. Ion implantation induces uniaxial out-of-plane strain, while the in-plane strain remains fixed due to epitaxial constraint. We show that this kind of uniaxial strain engineering effectively leads to polarization rotation from in-plane towards out-of-plane as the uniaxial strain is increasing. We find that this polarization rotation can be achieved via two different mechanisms: (i) via a sequence of phase transitions related to changes of crystal symmetries and (ii) via a continuous shift of the ferroelectric domain ratio towards out-of-plane oriented domains.

Keywords: ion implantation; ferroelectric domain configuration; strain engineering