Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session A53: Multiferroics, Magnetoelectrics, Spin-Electric Coupling, and Ferroelectrics - 1
8:00 AM–10:36 AM,
Monday, March 15, 2021
Sponsoring
Units:
DMP DCOMP GMAG
Chair: Turan Birol, University of Minnesota
Abstract: A53.00007 : Unconventional ferroelectricity from competing states in perovskites*
9:12 AM–9:48 AM
Live
Presenter:
Michele Kotiuga
(Ecole Polytechnique Federale de Lausanne)
Author:
Michele Kotiuga
(Ecole Polytechnique Federale de Lausanne)
Barium Titanate (BTO), the prototypical perovskite ferroelectric, built the foundation for the general understanding of ferroelectricity. The ferroelectric transitions of BTO are now understood to be a combination of a displacive model, driven by a soft phonon, and an order-disorder model. I will discuss a systematic method to find all microscopic prototypical orderings that are commensurate with the macroscopic symmetry. We have used these prototypes to systematically search for metastable phases, mapping out the potential energy landscape of BTO and relating the local minima to unstable phonons of the primitive cell. Using this methodology, I will briefly present a medium-throughput study of a number of perovskites.
Octahedral tilts, hosted by many perovskites, can present an insurmountable energy barrier to the switching of these structures to their inversion-symmetry-related counterparts. In H-doped samarium nickelate, the H valence electron localizes on a nearby NiO6 octahedron, resulting in a local dipole. At a concentration of ¼ H per Ni, we find that the height of the barrier to move the localized electron to a neighboring NiO6 octahedron is sufficiently low to allow switching. The switched state is unrelated by symmetry to the initial state but equal in energy under epitaxial strain, resulting in a large change in polarization. We term this unconventional ferroelectric a “fraternal-twin” ferroelectric.
*Samsung Advanced Institute of Technology, ONR Grant N00014-17-1-2770
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