Spin-wave logic devices based on isotropic forward volume magnetostatic waves

Abstract

We propose the utilization of isotropic forward volume magneto-static spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves.Steadily advancing progress in modern information technology pushes the computation capabilities of common silicon-based digital logics towards fundamental quantum limits. This raises the problem of how to overcome these inherent problems. Furthermore, issues such as waste heat production demand for new approaches. 1,2 A potential alternative is wave-based computing. In particular, logic elements and devices based on collective excitations of the magnetization in the solid state -spin waves and their quanta magnons -have attracted attention in the recent years. 3-7 In a spin-wave device the information can be encoded into the phase or amplitude of the wave, and the information can be processed by employing interference between different waves as well as nonlinear interactions. This field is still in its infant state, but recent progress has demonstrated its large potential. 8,9 A cornerstone of wave-based logic elements is the majority gate, since it allows for a simple implementation of complex logic circuits and the processing of several boolean operations with a single gate structure. 7,10 In a previous study, we introduced the design of an in-plane magnetized spin-wave majority gate. 7 It consists of three input waveguides where spin waves are excited, a symmetric spin-wave combiner which merges the different input waveguides, and an output waveguide where a spin wave propagates with the same phase as the majority of the input waves. In the combiner region scattering processes into higher-order dipolar spin-wave modes and small-wavelength exchange spin waves occur due to the broken translational symmetry of the waveguide system and the anisotropic dispersion relation of the spin waves in this magnetization configuration. We showed, that parasitic scattering processes into higher dipolar modes can be suppressed with a suitable waveguide geometry.But still, the output signal is influenced by exchange spin waves. 7 To overcome these limitations the use of isotropic forward volume magneto-static spin waves (FVMSW) is an interesting option, which thus implies the necessity of a new suitable majority gate design. Here, we demonstrate the functionality of an out-of-plane magnetized spin-wave majority gate which operates with isotropic forward volume magneto-static spin waves (FVMSW) and, thus, overcomes the limitations of the in-plane magnetized gates. We employ numerical simulat...

Magnonic crystals for data processing

“…• Two different designs of a micro-scaled majority gate for the processing of digital information were proposed and studied using numerical simulations [239,240] and experimentally [243]. Their functionality was proven.…”

“…To overcome these limitations, isotropic forward-volume magnetostatic spin waves were used in [240]. Moreover, a high spin-wave transmission through the gate of up to 64%, which is about three times that for an in-plane magnetized gate, was achieved [240]. A new asymmetric design of the majority gate has been proposed for this purpose.…”

“…Still, the output signal in [239] was influenced by exchange spin waves of the same frequency but much shorter wavelengths. To overcome these limitations, isotropic forward-volume magnetostatic spin waves were used in [240]. Moreover, a high spin-wave transmission through the gate of up to 64%, which is about three times that for an in-plane magnetized gate, was achieved [240].…”

Spin-Torque Excitation of Perpendicular Standing Spin Waves in Coupled YIG/Co Heterostructures

“…Magnonics based on exchange spin waves is particularly appealing, due to isotropic spin-wave propagation with small wavelengths and large group velocities [5]. With its long magnon propagation length, yttrium iron garnet (YIG) is especially interesting for this application.…”

Spin wave absorber generated by artificial surface anisotropy for spin wave device network

“…Among the different types of SWs, only magnetostatic forward volume waves (MSFVWs) possess isotropic dispersion property. 9 The recent development of the epitaxial growth technique, which employs pulsed laser deposition, for ultra-thin magnetic insulators such as yttrium iron garnet (YIG) has furthered progress towards the realization of practical SWDs, 10,11 because such insulators yield magnetic damping that is several orders of magnitude less than that of metallic magnetic waveguides. [12][13][14] However, because of the long attenuation lengths in YIG waveguides, unexpected standing modes are easily generated due to the SW reflection from the waveguide edge.…”