Strain engineering in lead zirconate titanate thin films: Reversible ferroelastic domain switching and giant electromechanical response

Abstract

Piezoelectric thin films are essential building blocks for next-generation microelectromechanical systems (MEMS). However, their functional performance has historically been limited by substrate mechanical constraints—a phenomenon known as the “clamping effect.” This phenomenon typically suppresses ferroelectric- and ferroelastic-domain mobilities. This review summarizes a paradigm shift in thin-film design: it redefines substrate clamping as a vital “restoring force” that ensures reversible domain switching rather than viewing it as purely degradative. By implementing a “hybrid strain engineering” approach that precisely tunes epitaxial and thermal strains in lead zirconate titanate thin films, our group demonstrates the feasibility of maximizing extrinsic contributions from non-180° (ferroelastic) domain-wall motion. Employing in situ synchrotron X-ray diffraction (XRD) at SPring-8, our group provides direct evidence of ultrafast, reversible 90°-domain switching at megahertz frequencies. This design guideline enables the giant piezoelectric responses in MEMS cantilevers, outperforming conventional clamped films and providing a scalable path for Beyond 5G/6G communication technologies and high-efficiency actuators.