Using surface plasmons to detect spin inertia

TL;DR

This paper explores how spin inertia in metallic magnets can generate nutation spin waves that hybridize with surface plasmons in 2D materials, offering a universal method to measure spin inertia.

Contribution

It introduces a novel mechanism linking spin inertia to hybrid spin wave-plasmon modes and proposes a spectroscopic method to quantify spin inertia in magnetic systems.

Findings

Spin inertia induces nutation spin waves in the terahertz regime.

Hybridization of spin waves with surface plasmons occurs in 2D magnetic heterostructures.

A spectroscopic approach to measure spin inertia universally in magnetic insulators.

Abstract

Recent experiments demonstrate that spin dynamics may acquire an inertial effect in a few metallic magnets, deviating from the traditional inertia-free dynamics. It remains an open question to ascertain the physical mechanisms and universality of the spin inertia across diverse magnetic systems. Here, we show that spin inertia generates nutation spin waves in the terahertz regime, which can hybridize with the surface plasmons in two-dimensional (2D) conducting materials such as graphene. By exciting hybrid spin wave-plasmon modes and analyzing the reflection spectrum of a 2D material$|$magnet heterostructure, we propose a method to quantitatively determine the strength of spin inertia in magnetic layers. Our approach is universally applicable to all types of magnetic insulators and could advance the future exploration of the magnitude and physical mechanism of spin inertia.