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arXiv · 1510.06835

The origin of hyperferroelectricity in Li$B$O$_3$ ($B$=V, Nb, Ta, Os)

Pengfei Li·Xinguo Ren·Guang-Can Guo·Lixin He
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Abstract

The electronic and structural properties of Li$B$O$_3$ ($B$=V, Nb, Ta, Os) are investigated via first-principles methods. We show that Li$B$O$_3$ belong to the recently proposed hyperferroelectrics, i.e., they all have unstable longitudinal optic phonon modes. Especially, the ferroelectric-like instability in the metal LiOsO$_3$, whose optical dielectric constant goes to infinity, is a limiting case of hyperferroelectrics. Via an effective Hamiltonian, we further show that, in contrast to normal proper ferroelectricity, in which the ferroelectric instability usually comes from long-range coulomb interactions, the hyperferroelectric instability is due to the structure instability driven by short-range interactions. This could happen in systems with large ion size mismatches, which therefore provides a useful guidance in searching for novel hyperferroelectrics.

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Pengfei Li, Xinguo Ren, Guang-Can Guo, Lixin He. 2015-10-23. The origin of hyperferroelectricity in Li$B$O$_3$ ($B$=V, Nb, Ta, Os). https://arxiv.org/abs/1510.06835

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