Microwave excitation of spin wave beams in thin ferromagnetic films.

P Gruszecki,M Krawczyk,A E Serebryannikov,M Kasprzak,W Śmigaj

doi:10.1038/srep22367

P Gruszecki, M Krawczyk + Show 3 more

Open Access

https://doi.org/10.1038/srep22367

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Abstract

An inherent element of research and applications in photonics is a beam of light. In magnonics, which is the magnetic counterpart of photonics, where spin waves are used instead of electromagnetic waves to transmit and process information, the lack of a beam source limits exploration. Here, we present an approach enabling generation of narrow spin wave beams in thin homogeneous nanosized ferromagnetic films by microwave current. We show that the desired beam-type behavior can be achieved with the aid of a properly designed coplanar waveguide transducer generating a nonuniform microwave magnetic field. We test this idea using micromagnetic simulations, confirming numerically that the resulting spin wave beams propagate over distances of several micrometers. The proposed approach requires neither inhomogeneity of the ferromagnetic film nor nonuniformity of the biasing magnetic field. It can be generalized to different magnetization configurations and yield multiple spin wave beams of different width at the same frequency.

Highlights

An inherent element of research and applications in photonics is a beam of light
It is closely related to photonics, which deals with electromagnetic waves, and phononics, which is concerned with elastic waves
We propose and numerically validate with micromagnetic simulations (MSs) a method of excitation of narrow spin wave (SW) beams in homogeneous ferromagnetic thin films using the microwave-frequency magnetic field generated by coplanar waveguides (CPWs) transducers with a suitable geometry

Summary

Introduction

An inherent element of research and applications in photonics is a beam of light. In magnonics, which is the magnetic counterpart of photonics, where spin waves are used instead of electromagnetic waves to transmit and process information, the lack of a beam source limits exploration. We show that the desired beam-type behavior can be achieved with the aid of a properly designed coplanar waveguide transducer generating a nonuniform microwave magnetic field We test this idea using micromagnetic simulations, confirming numerically that the resulting spin wave beams propagate over distances of several micrometers. We propose and numerically validate with micromagnetic simulations (MSs) a method of excitation of narrow SW beams in homogeneous ferromagnetic thin films using the microwave-frequency (mf) magnetic field generated by CPW transducers with a suitable geometry. We exploit the fact that efficient excitation of an SW can occur only when the Fourier transform of the mf magnetic field has a large magnitude at the wave vector equal to the SW wave vector at the excitation frequency To ensure that this condition holds only locally, we vary the transducer’s profile along the mf current flow direction. Other possible scenarios and applications will be discussed in this paper

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