Field-Induced Structural Dynamics of Polarization Switching in Hf<sub>x</sub>Zr<sub>1-x</sub>O<sub>2</sub> Thin Films.

Lee, Sangjun; Kim, Sunghyun; Park, Seong Yong; Kim, Donghyun; Lee, Su Yong; Ham, Daseul; Lee, Hyun Hwi; Yun, Dongjin et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

The polarization characteristics of Hf<sub>x</sub>Zr<sub>1-x</sub>O<sub>2</sub> (HZO) are intrinsically linked to its crystal structure. Optimizing its functionality in ferroelectric (FE) and antiferroelectric (AFE) devices requires understanding the structural evolution during polarization switching, which remains insufficiently understood. Here, the switching mechanism in HZO thin films is elucidated by combining in situ microbeam grazing incidence X-ray diffraction and first-principles-based metadynamics simulations, providing unambiguous evidence of phase evolution. Across compositions (x = 0 to 0.5), switching involves reversible transitions between the nonpolar tetragonal (t) P4<sub>2</sub>/nmc and polar orthorhombic (o) Pca2<sub>1</sub> phases. Zr-rich AFE compounds undergo a complete t-phase transition during polarization reversal, while in Hf-rich FE compounds, transient t-phase formation facilitates the nucleation and growth of o-phase domains with reversed polarization. This study promotes engineering phase evolution in HZO for advanced devices.