Self‐Imaging Based Programmable Spin‐Wave Lookup Tables

Abstract

oscillations propagating without charge transfer in magnetic materials. [2][3][4][5] This property, combined with a wider range of available frequencies than in electronics and the ability to encode information both in amplitude and phase, makes SWs an important candidate for an information carrier in a new generation of computing devices, where Joule-Lenz heat and other obstacles may be significantly reduced. [6][7][8][9] Magnonic circuits (systems utilizing SWs) [10,11] may consist of waveguides through which SWs propagate, [12][13][14][15] and interference areas at crossings, for example, for creating majority gates. [16][17][18][19][20] The waveguides may also couple with other waveguides [21,22] to implement a logical operation. In this manner, it has been possible to demonstrate a 32-bit magnonic full adder [21] and SWbased approximate 4:2 compressor. [23] Another strategy is to use wide ferromagnetic film areas for SW operation and narrow waveguides as SW inputs. This approach was used to redirect [24][25][26] and process SWs. [27][28][29][30][31][32] Operation of these systems is based on the interference of incoming SWs. Therefore, a local modification of the medium (the magnonic equivalent of the refractive index) in which SWs propagate is crucial to design and optimize its functionality. It was recently shown that it could be achieved by an introduction of defects in so-called inverse design approach, [32] placement of programmable magnetic elements on top of that region, [30] or utilization of noncolinear magnetization textures. [33][34][35] This interference based strategy appears promising also for the realization of physical neural networks operating on SWs. [30,33] Thereby, interference effects open a promising avenue for the development of SWbased beyond-CMOS solutions.A plane wave passing through a system of periodically spaced obstacles (diffraction gratings or holes) interferes, creating a characteristic diffraction pattern in the near field, reproducing the grating image at specific distances from the input apertures. This phenomenon is known as the Talbot or the selfimaging effect, and was observed for light already in the 19th century. [36] The resulting interference pattern is called a Talbot carpet, and we have recently theoretically demonstrated that this effect can also occur for SWs. [37] The properties of Talbot carpets created by SWs strongly depend on material parameters, geometry, type, thickness of a magnetic material, and on dynamic parameters such as wavelength, orientation, and the value of an external magnetic field.Here, we exploit the self-imaging phenomenon occurring in a thin ferromagnetic multimode waveguide with SWs introduced by periodically spaced single-mode input waveguides. SWs entering the multimode waveguide have a controllable phase. In particular, we present a new class of reprogrammable magnonic blocks implementing array indexing operations.Inclusion of spin waves into the computing paradigm, where complementary metal-oxide-semiconductor devices are still at th...

Spin‐Wave Optics in YIG Realized by Ion‐Beam Irradiation

“…Thus, spin waves are not an ideal fit to directly replicate classical optical building blocks, instead, they are more suitable for the approaches used in nanophotonics [9,34] -we believe that our technique is also applicable to the realization of such structures, as the achievable resolution with FIB (≈10 nm) can easily serve that. The automatic design of magnonic devices combined with a flexible and versatile fabrication method has the potential to raise the bar for magnonic device concepts, enabling the realization of circuits, [35] and drive the field toward practical applications.…”

Magnon-Optic Effects with Spin-Wave Leaky Modes: Tunable Goos-Hänchen Shift and Wood’s Anomaly

“…An intriguing wave type is the spin wave (SW), that is, a collective precessional disturbance of magnetization in magnetic materials, which is believed to be a promising candidate for information carriers in beyond-CMOS devices. − SW optics is more complex than its electromagnetic counterpart and rich in optical phenomena. − Many effects from photonics have already been transferred to magnonics, for instance, negative refraction, anomalous refraction, graded refractive index effects, − and the Goos-Hänchen (GH) effect, i.e., the lateral shift of the waves’ reflection point at an interface. − While the GH effect has been predicted theoretically, it has not yet been experimentally observed for SW beams. Also, the BICs, LMs, Wood’s anomalies, and resonance effects widely explored in photonics remain poorly investigated in magnonics.…”