Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

Abstract

We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

Chiral magnonic resonators: Rediscovering the basic magnetic chirality in magnonics

“…The discussion above suggests that the use of arrays could broaden the bandwidth but only somewhat: the reliance on the frequency resonance in individual resonators would be weakened but another restriction would emerge insteadthat of the Bragg resonance. 29,[40][41][42] Before discussing the control resonator from Fig. 4, we note that it is actually optional.…”

“…A common feature of the relevant recent studies, such as those from Refs. [25][26][27][28][29][30]33,[39][40][41][42]44,46, is the translational symmetry of the media in the direction parallel to the resonators' long axis. However, the expanding availability and use of laterally confined YIG magnonic waveguides 54,56 urges their implementation with chiral magnonic resonators, e.g.…”

“…One does not need to stick to one dimensional (1D) designs, such as finite resonators on 1D stripe waveguides 15,16 and infinitely long resonators on thin film media. Instead, one could form 2D systems (which could be periodic 41,[78][79][80] or irregular) of finite resonators e.g. on continuous thin films of YIG (Fig.…”

Parametric Generation of Propagating Spin Waves in Ultrathin Yttrium Iron Garnet Waveguides

“…[20][21][22][23][24] Most of the mentioned devices utilize SWs in yttrium iron garnets (YIG) due to their ultralow magnetic losses. [1,[25][26][27][28] However, downscaling those elements toward nanometer sizes is the basic requirement toward integrated magnonics, where the magnons are controlled by magnons themselves. In principle, downscaling leads to a strong quantization of the energy levels and, consequently, to the appearance of distinct SW bands in the magnon spectrum.…”

“…So far, several devices for this aim have been either proposed or realized, including magnonic crystals, directional couplers, majority gates, (de)multiplexers, transistors, and various logic elements . Most of the mentioned devices utilize SWs in yttrium iron garnets (YIG) due to their ultralow magnetic losses . However, downscaling those elements toward nanometer sizes is the basic requirement toward integrated magnonics, where the magnons are controlled by magnons themselves.…”