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arXiv · 2103.16466

Electron-lattice coupling contributions to polarization switching in charge-order-induced ferroelectrics

Yubo Qi·Karin M. Rabe
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Abstract

We carry out first-principles density-functional-theory calculations to elucidate the polarization switching mechanism in charge-ordering-induced ferroelectrics based on the prototypical case of the (SrVO$_3$)$_1$(LaVO$_3$)$_1$ superlattice. We find that lattice relaxation for a specific charge ordering state can "lock" that state in, making non-adiabatic switching to a different CO variant energetically prohibitive, and in some cases, even making the energy barrier for adiabatic switching prohibitively large. We classify charge-ordering materials into two types, polyhedral breathing and off-centering displacement, based on the type of lattice mode most strongly coupled to the charge ordering. We demonstrate that the non-adiabatic electron hopping induced by an external electric field is expected only in off-centering-displacement-type charge-ordering-induced ferroelectrics. This successfully explains the different observed switching behaviors of LuFe$_2$O$_4$ and Fe$_3$O$_4$. These results offer a new understanding of the polarization switching mechanism in charge-ordering-induced ferroelectrics that provides guidance for the design and discovery of charge-ordering-induced ferroelectric materials and suggests a strategy for realizing "electronic ferroelectricity" with polarization switching on electronic rather than lattice time scales.

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Yubo Qi, Karin M. Rabe. 2022-02-18. Electron-lattice coupling contributions to polarization switching in charge-order-induced ferroelectrics. https://doi.org/10.1103/physrevb.106.125131

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