Self-hybridization and tunable magnon-magnon coupling in van der Waals synthetic magnets

TL;DR

This paper investigates tunable magnon-magnon interactions in van der Waals layered antiferromagnetic materials, revealing a self-hybridization effect and demonstrating electrical control over magnon spectra for potential quantum magnonic devices.

Contribution

It introduces the concept of self-hybridization in van der Waals antiferromagnets and shows how to electrically tune magnon-magnon coupling and energy level crossings.

Findings

Self-hybridization occurs between optical or acoustic magnons.

Magnon mode frequencies are highly sensitive to layer number.

Electrical control can modulate the strength of magnon interactions.

Abstract

Van der Waals magnets are uniquely positioned at the intersection between two-dimensional materials, antiferromagnetic spintronics, and magnonics. The interlayer exchange interaction in these materials enables antiferromagnetic resonances to be accessed at GHz frequencies. Consequently, these layered antiferromagnets are intriguing materials out of which quantum hybrid magnonic devices can be fashioned. Here, we use both a modified macrospin model and micromagnetic simulations to demonstrate a comprehensive antiferromagnetic resonance spectra in van der Waals magnets near the ultrathin (monolayer) limit. The number of optical and acoustic magnon modes, as well as the mode frequencies, are found to be exquisitely sensitive to the number of layers. We discover a self-hybridization effect where pairs of either optical or acoustic magnons are found to interact and self-hybridize through the dynamic exchange interaction. This leads to characteristic avoided energy level crossings in the energy spectra. Through simulations, we show that by electrically controlling the damping of surface layers within heterostructures both the strength and number of avoided energy level crossings in the magnon spectra can be controlled.