Manipulating polar structures in freestanding antiferroelectric and ferroelectric membranes

Polar oxides display remarkable properties relevant for a wide number of applications such as non-volatile memories or energy conversion (thermal, mechanical, solar, chemical). Over the last 30 years, via different materials engineering processes (e.g. epitaxial strain or defect engineering), researchers have learned to tune and optimize the properties of these materials (1), however their inherent strong chemical bonds have prevented from exploiting the mechanical flexibility and heterointegration possibilities offered by exfoliable materials such as semiconducting dichalcogenides or layered oxides. Nowadays, with the recent developments of sacrificial layers compatible for the growth of perovskite films and for their substrate release, the synthesis of single-crystal membranes of perovskite oxides has become more accessible, enabling their integration CMOS processing or flexible electronics via near room temperature processes, or expanding the strategies for thermal, mechanical or optical actuation of these materials (2).

In this talk I will show recent progress on the synthesis and manipulation of polar ordering in ferroelectric and antiferroelectric nanomembranes and capacitors, fabricated after releasing epitaxial heterostructures grown on compatible oxide substrates. The consequences of the release from the substrate clamping on the polarization switching dynamics and energetics will be discussed for BaTiO₃ ferroelectric capacitors (3, 4), as well as for antiferroelectric PbZrO₃ capacitors, transferred to silicon. Freed from the mechanical constraints from the substrate, the freestanding membranes are susceptible to internal and external strains that allow manipulating their functional responses. In this regard, I will discuss the effect of interlayer stresses and substrate bending for the macroscopic control of electrical properties, and the impact of local strains at spontaneously occurring folding patterns in the membranes, favoring the emergence of complex domain patterns and functional domain walls.

1. A. Fernandez, et al., Adv. Mater. 34, 2108841 (2022).

2. D. Pesquera, et al.. J. Phys. Condens. Matter. 34, 383001 (2022).

3. D. Pesquera, et al.. Adv. Mater. 32, 2003780 (2020).