Physical Review Letters 134, 056802 (2025)

Origin of Interstitial Doping Induced Coercive Field Reduction in Ferroelectric Hafnia

Tianyuan Zhu1,2,*, Liyang Ma1,*, Xu Duan3, Shiqing Deng4, and Shi Liu1,2,†
1. Westlake University  |  2. Westlake Institute for Advanced Study
3. Zhejiang University of Science and Technology  |  4. USTB

The Challenge

Hafnia-based ferroelectrics are promising for nonvolatile memory, but the high coercive field required for switching is a major obstacle. Recent experiments showed reduced coercive fields with interstitial doping, but the mechanism was unclear.

Methodology

Using Density Functional Theory (DFT) and large-scale deep potential molecular dynamics simulations, we modeled the Pca21 phase with interstitial Hf dopants to explain experimental observations.

Key Insights

  • Minimal Model: The Pca21 phase with moderate interstitial Hf dopants explains the reduction, rather than the rhombohedral phase.
  • Mechanism: Interstitial defects facilitate polarization reversal by promoting Pbcn-like mobile 180° domain walls.
  • Optimization: High-throughput calculations reveal a negative correlation between switching barrier and dopant size.
< 1 MV/cm Reduced Switching Field (with Prepoling)