Dynamical breaking of inversion symmetry, strong second harmonic generation, and ferroelectricity with nonlinear phonons

Egor I. Kiselev

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arXiv · 2510.12990

Dynamical breaking of inversion symmetry, strong second harmonic generation, and ferroelectricity with nonlinear phonons

Egor I. Kiselev

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Abstract

We show how crystalline inversion symmetry can be dynamically broken by optical phonons with generic, hardening Kerr-like non-linearities. The symmetry-broken state is reached through a parametric instability that can be accessed by driving close to half the phonon resonance. After the onset of the instability, the system settles to a steady state with inversion-symmetry breaking phonon trajectories and strong second harmonic generation. The time averaged positions of the atoms are displaced relative to equilibrium, resulting in a ferroelectric rectification of the driving signal.

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Egor I. Kiselev. 2025-10-14. Dynamical breaking of inversion symmetry, strong second harmonic generation, and ferroelectricity with nonlinear phonons. https://arxiv.org/abs/2510.12990

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