# A generalized model of magnon kinetics and subgap magnetic noise

Source: [A generalized model of magnon kinetics and subgap magnetic noise](<https://www.sota2.com/research/paper/68fa41b91e209131ce8fcfda>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-25T03:26:08.978Z

Authors: Haocheng Fang, Shu Zhang, Yaroslav Tserkovnyak

Published: 2021-11-24T16:39:19.000Z

## Abstract

Magnetic noise spectroscopy provides a noninvasive probe of spin dynamics in magnetic materials. We consider two-dimensional magnetically ordered insulators with magnon excitations, especially those supporting long-distance magnon transport, where nitrogen-vacancy (NV) centers enable the access to (nearly) ballistic transport regime of magnons. We develop a generalized theory to describe the magnon transport across a wide range of length scales. The longitudinal dynamic spin susceptibility is derived from the Boltzmann equation and extended to a Lindhard form, which is modified by both the spin-conserving magnon collisions and spin relaxation. Our result is consistent with the diffusive (ballistic) model for the length scale much larger (smaller) than the magnon mean free path, and provides a description for the intermediate regime. We also give a prediction for the NV transition rate in different magnon transport regimes.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/2111.12613>)

[PDF](<https://arxiv.org/pdf/2111.12613.pdf>)