Fluorite oxides such as HfO2 exhibit rich and tunable phase behavior, making them promising candidates for next generation electronic devices. A key challenge is to design amorphous HfO2-based high-k materials with both structural and performance stability. Here, using molecular dynamics simulations supported by experimental measurements, we reveal that Ba doping stimulates a polyamorphic transition in HfO2, yielding a semi-ordered amorphous (SA) phase characterized by disordered oxygens embedded within an ordered metal sublattice. We find that this phase arises from degenerate short-range symmetry breaking modes, consistent with Pauling's parsimony rule. Notably, the SA structure is thermodynamically stable and displays a wider bandgap and higher dielectric constant than conventional random-packing amorphous structure, owing to suppressed subgap states and increased Born effective charges. We further demonstrate that this structural motif generalizes to Ba-, Sr-, and Ca-doped HfO2 and ZrO2, establishing a broadly applicable strategy for designing high-performance amorphous dielectrics.
@article{arxiv.2506.18333,
title = {Doping-induced Polyamorphic Transitions in Fluorite Oxides},
author = {Hao Yang and Qiaotong Luan and Qing Zhang and Yuhao Yue and Yawen Xu and Xiaohui Liu and Zheng Wen and Zhaoru Sun},
journal= {arXiv preprint arXiv:2506.18333},
year = {2025}
}