Reversable phase transitions in ferroic two-dimensional Nb2O2I4 through optically excited coherent phonons

TL;DR

This study demonstrates that tailored laser pulses can induce reversible phase transitions in 2D Nb2O2I4, enabling control over multiple ferroic phases for potential electronic storage applications.

Contribution

The paper shows how specific optical excitations can reversibly switch between ferroic phases in 2D Nb2O2I4, revealing new ferroic states and control mechanisms.

Findings

Laser pulses activate specific coherent phonon modes.

Reversible transitions between ferroelectric, antiferroelectric, and ferrielectric phases.

Multiple ferroic phases can be optically induced and reverted.

Abstract

We investigate optically induced phase transitions in the two-dimensional (2D) ferroelectric (FE) material Nb2O2I4 using real-time time-dependent density functional theory (rt-TDDFT). Our results demonstrate that tailored laser pulses can activate specific coherent phonon modes. Specifically, the anharmonic atomic distortions of the A1-1 and A1-2 modes at the {\Gamma}-point facilitate the reversal of in-plane polarization. By fine-tuning laser parameters, additional phonon modes at both the Y and {\Gamma} points are excited. The resulting nonequilibrium atomic dynamics enable the formation of previously unreported ferroic phases, including three antiferroelectric (AFE) phases and one ferrielectric (FiE) phase. Notably, these optically induced phases can be reverted to the initial FE state using appropriate techniques. This controllable reversibility among multiple ferroic phases positions 2D Nb2O2I4 as a highly promising candidate for next-generation electronic storage applications.