2D Surface Spin Waves in Dynamic Magnonic Crystals Created by a Surface Acoustic Wave in YIG Films

Alexander V Medved

doi:10.11648/j.ajpa.20210905.12

Abstract

Some results of the study of 2D propagation of surface magnetostatic spin waves (SMSW) in dynamic magnonic crystals (DMC) created by a surface acoustic wave (SAW) in a structure with a yttrium-iron garnet (YIG) film are presented. Such studies are interesting from the practical point of view of creating real relatively complex devices on spin waves when they propagate in different directions, and not only in the 1D case. The methods of experimental research are presented, in particular, the features of the method of excitation of SAW in the structure that do not lead to the appearance of additional magnetic anisotropy in it, a method for measuring the angular dependencies of SMSW using mobile antenna–probes is presented. The angular dependences of the magnonic band gap frequencies are measured. It is established that the transmission bands with the transformation of the reflected SMSW into other types of magnetostatic waves (MSW) exist at any angle values, while the intervals in which there are no SMSW transformations during reflections occur in a certain narrower range of angles. The angles of the directions of the wave vectors and the Poynting vector of the reflected SMSW were also measured. A satisfactory agreement was obtained with the calculation performed using the method of isofrequency curves and the laws of inelastic scattering SMSW on SAW.

Highlights

The «magnonic crystals», by analogy with photonic crystals, denote a magnetic medium with artificially created periodic magnetic inhomogeneities [1,2,3]
Medved: 2D Surface Spin Waves in Dynamic Magnonic Crystals Created by a Surface Acoustic Wave in yttrium-iron garnet (YIG) Films propagation as a function of the angles between the surface magnetostatic spin waves (SMSW) and surface acoustic wave (SAW) wave vectors in the dynamic magnonic crystals (DMC) in the plane of the YIGGGG structure are presented
In our experiments with DMC in the "on-pass" method, at the angle between the wave vectors of the incident SMSW and SAW β=0, an essentially onedimensional geometry is realized, which was studied in our previous works

Summary

Introduction

The «magnonic crystals», by analogy with photonic crystals, denote a magnetic medium with artificially created periodic magnetic inhomogeneities [1,2,3]. Medved: 2D Surface Spin Waves in Dynamic Magnonic Crystals Created by a Surface Acoustic Wave in YIG Films propagation as a function of the angles between the SMSW and SAW wave vectors in the DMC in the plane of the YIGGGG structure are presented. The experimental results obtained are compared with the corresponding theoretical dependences obtained graphically using the method of isofrequency curves [23], known in geometric optics, and the previously developed theory of inelastic scattering of SMSW on acoustic waves [12,13,14,15,16,17] - the phenomenon underlying the operation of dynamic magnonic crystals created by propagating acoustic waves in magnetic materials. The results described in our article can be used in the development of new 2-D spin-waves devices and the study of 2-D spin wave propagation processes

Experimental Technique

Experimental Results and Discussion

Conclusion