%0 Journal Article
%A Rushchanskii, Konstantin
%A Blügel, Stefan
%A Ležaić, Marjana
%T Ordering of Oxygen Vacancies and Related Ferroelectric Properties in HfO 2 − δ
%J Physical review letters
%V 127
%N 8
%@ 0031-9007
%C College Park, Md.
%I APS
%M FZJ-2021-05040
%P 087602
%D 2021
%X Using density functional theory combined with an evolutionary algorithm, we investigate ferroelectricity in substoichiometric HfO2−δ with fixed composition δ=0.25. We find that oxygen vacancies tend to cluster in the form of two-dimensional extended defects, revealing several patterns of local relative arrangements within an energy range of 100 meV per Hf atom. Two lowest-energy patterns result in polar monoclinic structures with different transformation properties. The lowest one elastically transforms to the ferroelectric orthorhombic structure via a shear deformation, overcoming an energy barrier, which is more than twice lower than in the stoichiometric hafnia. The second-lowest structure transforms at smaller volumes to a nonpolar tetragonal one. We discuss the experimentally observed wake-up effect, fatigue, and imprint in HfO2-based ferroelectrics in terms of different local ordering of oxygen-vacancy extended defects, which favor specific crystallographic phases.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ 34477424
%U <Go to ISI:>//WOS:000686914800016
%R 10.1103/PhysRevLett.127.087602
%U https://juser.fz-juelich.de/record/903349