Evidence of standing spin-waves in a van der Waals magnetic material

Abstract

Spin-waves have been studied for data storage, communication and logic circuits in the field of spintronics based on their potential to substitute electrons [1,2]. Recent discovery of magnetism in two-dimensional (2D) systems such as monolayer CrI3 and Cr2Ge2Te6 has led to a renewed interest in such applications of magnetism in the 2D limit [3][4][5]. Here we present direct evidence of standing spin-waves along with the uniform precessional resonance modes in van der Waals magnetic material, CrCl3. Our experiment is the first direct observation of standing spin-wave modes, set up across a thickness of 20 µm, in a van der Waals material. We detect standing spin-waves in the vicinity of both, optical and acoustic, branches of the antiferromagnetic resonance. We also observe magnon-magnon coupling, softening of resonance modes with temperature and extract the evolution of interlayer exchange field as a function of temperature.

Cross-sublattice Spin Pumping and Magnon Level Attraction in van der Waals Antiferromagnets

“…To determine the spin current, we evaluate each term given by the Eqs. ( 23)- (22). Up to linear order in the Gilbert damping difference ∆ᾱ , we find e…”

“…Below, we present examples of spin pumping current, evaluating Eqs. (21)(22)(23), due to the coherent magnonic excitation by linearly polarized external ac fields.…”

“…Capitalizing on these features, magnon-magnon coupling resulting in level repulsion and hybridization has recently been observed in the vdW AF CrCl 3 [21][22][23]. Approaching the challenge from a different direction, similar magnonic hybridization via their mutual coupling [24][25][26] has been discovered in carefully chosen platforms including compensated ferrimagnets [27] and synthetic AFs [28,29].…”

“…nonzero ∆ ᾱ. While a "reactive" coupling between magnon modes has been observed in various systems [21,22,[27][28][29], dissipative coupling remains less explored and invokes non-Hermitian…”