Low-lying magnon frequency comb in skymion crystals

TL;DR

This paper demonstrates a low-lying magnon frequency comb in skyrmion crystals, enabling efficient nonlinear frequency conversion and potential applications in quantum information and precision measurement.

Contribution

It introduces a novel low-lying MFC in skyrmion crystals originating from three-wave mixing, improving efficiency and enabling new applications.

Findings

MFC frequencies are below the ferromagnetic resonance.

MFC arises from three-wave mixing between skyrmion gyration and breathing modes.

Enhanced nonlinear frequency conversion efficiency.

Abstract

A stable, low-power and tunable magnon frequency comb (MFC) is crucial for magnon-based precision measurements, quantum information processing and chip integration. Original method for creating MFC utilizes the nonlinear interactions between propagating spin waves and localized oscillations of an isolated magnetic texture, e.g., skyrmion. It requires a driving frequency well above the ferromagnetic resonance (FMR) and the spectrum frequency of MFC will quickly approach to the detection limit of conventional microwave technique after only tens of comb teeth. In addition, the detection and manipulation of a single skyrmion is challenging in experiments due to its high degree of locality. These issues hinder the applications of MFC. In this work, we report the low-lying MFC with comb frequencies below the FMR in a skyrmion crystal (SkX). We show that the MFC originates from the three-wave mixing between the collective skyrmion gyration and breathing in the SkX. Our findings significantly improve the efficiency of the nonlinear frequency conversion from a single-frequency mircowave input, and establish a synergistic relationship between the SkX and MFC, which paves the way to coherent information processing and ultra-sensitive metrology based on MFC.