Phase control of magnons in the van der Waals antiferromagnet NiPS$_3$

TL;DR

This paper demonstrates optical phase control of magnons in NiPS$_3$, enabling continuous tuning of spin precession phase through polarization manipulation, with potential applications in spin-wave devices and ultrafast information processing.

Contribution

It introduces a method for controlling magnon phase in a van der Waals antiferromagnet using polarized light, allowing continuous phase tuning.

Findings

Magnon phase can be tuned from 0 to 2π by polarization control.

Reversing helicity or rotating linear polarization affects the sign of spin precession.

Optical excitation pathways have comparable efficiency, enabling phase control.

Abstract

We demonstrate phase control of magnons in the van der Waals antiferromagnet NiPS$_3$ using optical excitation by polarized light. The sign of the coherent precession of spin amplitude changes upon (1) reversing the helicity of a circularly polarized pump beam, or (2) rotating the polarization of a linearly polarized pump by $\pi/2$. Because these two excitation pathways have comparable generation efficiency, the phase of spin precession can be continuously tuned from 0 to $2\pi$ by controlling the polarization state of the pump pulse. The ability to excite magnons with a desired phase has potential applications in the design of a spin-wave phased array and ultrafast spin information processing.