Ultrafast switching of photoinduced phonon chirality in the antiferrochiral BPO$_{4}$ crystal

TL;DR

This study demonstrates that polarized ultrafast light can reversibly control and switch the chirality of phonons in BPO$_4$ crystals, enabling dynamic manipulation of lattice chirality and phonon-induced magnetization.

Contribution

The paper introduces a novel mechanism for ultrafast optical control of phonon chirality in antiferrochiral crystals using first-principles calculations and nonlinear phonon dynamics.

Findings

Polarized optical pumping induces and filters chiral phonons.

Chirality can be reversibly switched by tuning light polarization.

Pump-induced chiral phonons generate ultrafast phonon magnetization.

Abstract

In crystalline systems, chiral crystals cannot interconvert to their enantiomorph post-synthesis without undergoing melting-recrystallization processes. However, recent work indicates that ultrafast terahertz-polarized light has been shown to enable dynamic control of structural chirality in the antiferrochiral boron phosphate (BPO$_4$) crystal. Here, using first-principles calculations and nonlinear phonon dynamics simulations, we investigate the underlying physics of lattice dynamics in this system. The results demonstrate that polarized optical pumping not only induces chiral phonons but also establishes a chirality-selective filtering mechanism, both of which can be reversibly switched by tuning the polarization of the excitation pulse. Furthermore, under a temperature gradient, the pump-induced chiral phonons give rise to ultrafast phonon magnetization, with its direction also controllable via light polarization. Our findings establish a new paradigm for ultrafast optical control of phonon chirality via dynamic chirality switching, offering promising opportunities for chiral information transfer and the design of chiral phononic devices.