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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 28: Focus Session: (Multi-)Ferroic States IV
KFM 28.3: Talk
Thursday, March 21, 2024, 15:50–16:10, EMH 225
First-principles predictions of HfO2-based ferroelectric superlattices — •Binayak Mukherjee1, Natalya S. Fedorova1, and Jorge Íñiguez-González1,2 — 1Department of Materials Research and Technology, Luxembourg Institute of Science and Technology, L-4362, Esch-sur-Alzette, Luxembourg — 2Department of Physics and Materials Science, University of Luxembourg, L-4422, Belvaux, Luxembourg
The metastable nature of the polar phase of HfO2 is a significant impediment to its industrial application as a functional ferroelectric material. In fact, no polar phases exist in the bulk phase diagram of HfO2, which shows a non-polar monoclinic ground state, and this requires polar orthorhombic HfO2 to be kinetically stabilized. Here, we propose an alternative approach, demonstrating the feasibility of thermodynamically stabilizing polar HfO2 through superlattices with other simple oxides. Using the composition and stacking direction of the superlattice as design parameters, we obtain heterostructures that can be fully polar, fully antipolar or mixed, with improved energetics compared to the orthorhombic polar HfO2 in bulk form. Our results suggest that combining HfO2 with an oxide that does not have a monoclinic ground state generally drives the superlattice away from this non-polar phase, favoring the stability of the ferroelectric structures that minimize the elastic and electrostatic penalties. As such, these diverse and tunable superlattices hold promise for various applications in thin-film ferroelectric devices.
Keywords: Ferroelectricity; Hafnium oxide (HfO2); Superlattices; First-principles calculations