- By:
- Ghanbari, Reza; KP, Harikrishnan; Patel, Kinnary; Zhou, Hua; Zhou, Tao; Liu, Rui; Wu, Liyan; Khandelwal, Aarushi; Crust, Kevin; Hazra, Sankalpa; Carroll, John; Meyers, Cedric; Wang, Jiayue; Prosandeev, Sergey; Qiao, Huimin; Kim, Younghoon ; Nabei, Yoji; Chi, Miaofang ; Sun, Dali; Balke, Nina; Holt, Martin; Gopalan, Venkatraman; Spanier, Jonathan; Muller, David; Bellaiche, Laurent; Hwang, Harold; Xu, Ruijuan
- Journal Name:
- Nature Communications
- Page Number:
- 7766
- Volume:
- 16
- Issue Number:
- 1
- Publication Date:
- September 3, 2025
- View DOI Listing:
- https://doi.org/10.1038/s41467-025-63041-w
Abstract
Enhanced susceptibilities in ferroelectrics often arise near phase boundaries between competing ground states. While chemically-induced phase boundaries have enabled ultrahigh electrical and electromechanical responses in lead-based ferroelectrics, precise chemical tuning in lead-free alternatives, such as (K,Na)NbO3 thin films, remains challenging due to the high volatility of alkali metals. Here, we demonstrate strain-induced morphotropic phase boundary-like polymorphic nanodomain structures in chemically simple, lead-free, epitaxial NaNbO3 thin films. Combining ab initio simulations, thin-film epitaxy, scanning probe microscopy, synchrotron X-ray diffraction, and electron ptychography, we reveal a labyrinthine structure comprising coexisting monoclinic and bridging triclinic phases near a strain-induced phase boundary. The coexistence of energetically competing phases facilitates field-driven polarization rotation and phase transitions, giving rise to a multi-state polarization switching pathway and large enhancements in dielectric susceptibility and tunability across a broad frequency range. Our results open new possibilities for engineering lead-free thin films with enhanced functionalities for next-generation applications.
