Electrostriction-driven phase instability enables giant pseudo-piezoelectricity in Hf 0.5 Zr 0.5 O 2X
- Achilles Bergne
- Milica Vasiljevic
- Denis Alikin
- Victor Buratto Tinti
- Leonardo Oliveira
- Megan O. Landberg Hill
- Huaiyu Chen
- Jesper Wallentin
- Dylan Jennings
- Wolfgang Rheinheimer
- Henrik Bruus
- Mathias Grønborg
- Dimitrios Koukoulis
- Armando Antonio Morin-Martinez
- Javier Zamudio-García
- Ivano Eligio Castelli
- Reinis Ignatāns
- Andrei Kholkin
- Dennis Valbjørn Christensen
- Nini Pryds
- Vincenzo Esposito
2026-06-26
The electromechanical properties of hafnium zirconium oxide fluorite (Hf 0.5 Zr 0.5 O 2 , HZO) remain largely unexplored despite its widespread use as a ferroelectric in CMOS-compatible devices. Here, we demonstrate that electrostriction-driven phase instability enables a giant pseudo-piezoelectric response in epitaxial HZO thin films. Above a critical field of 24 kilovolts per centimeter, field-induced transitions between nonpolar and polar phases activate an extrinsic piezoelectric response of ~1000 picometers per volt and bias-stabilized pseudo-piezoelectric strains exceeding 10,000 picometers per volt. This behavior arises from a combination of large electrostriction ( M = 1 × 10 −14 square meters per square volt), ferroelastic softness, and structural reconfiguration, rather than intrinsic polarization switching. Multimodal characterization combining interferometry, diffraction methods, scanning probe microscopy, and first-principles modeling confirms the coupling between strain and metastable phase dynamics. These findings reveal a previously unrecognized mechanism for functional strain generation in fluorite oxides, positioning HZO as a versatile platform for strain-engineered actuators, adaptive metasurfaces, and reconfigurable nanoelectromechanical systems.