The design of a microstructured, fully functional spin-wave majority gate is presented and studied using micromagnetic simulations. This all-magnon logic gate consists of three-input waveguides, a spin-wave combiner and an output waveguide. In order to ensure the functionality of the device, the output waveguide is designed to perform spin-wave mode selection. We demonstrate that the gate evaluates the majority of the input signals coded into the spin-wave phase. Moreover, the all-magnon data processing device is used to perform logic AND-, OR-, NAND-and NOR-operations.In spintronics the degree of freedom of the spin is used to transmit information. Spin and, thus, angular momentum cannot only be transmitted by electrons, but also by magnons, the quanta of the dynamic excitations of the magnetic system -spin waves. It is possible to encode information in the phase or amplitude of such spin waves and to have it transmitted through spin-wave waveguides. Moreover, the wave properties allow for efficient data processing through the exploitation of the interference between spin waves.[1-8] An important step towards the application of spin-wave devices in modern information technology is the realization of spin-wave logic gates. In this context, the majority gate is of special interest since it allows for the evaluation of the majority of an odd number of input signals, as given in Tab. I. Furthermore, not only can majority operations be performed with this gate but also AND-or OR-operations, if one input (see input 3 in Tab. I) is used as a control input. Hence, the advantage of the majority gate is its configurability and functionality.[9] In a spin-wave majority gate the phase φ of the waves is used as an information carrier (φ 0 corresponds to logic "0", logic "1" is represented by φ 0 + π). Although the idea of such majority gates was presented earlier, [9,10] no practical realization suitable for the integration into magnonic circuits has thus far been proposed.One of the main problems of a realistic spin-wave majority gate is the coexistence of different spin-wave modes with different wavelengths at a fixed frequency in the structure.[11] As a result, the output signal is given by overlaying waves of various phases and, thus, the majority function is lost. As a solution, a design which guarantees for a single-mode operation has to be used. Here, we present the design of an all-magnon majority gate and prove its functionality using numerical simulations. The width of the output waveguide has been chosen in a way such as to obtain single-mode operation. The operational characteristics of the majority gate have been studied for different phases. AND-, OR-, NAND-and NOR-operations have been demonstrated using the same * Electronic address: klingles@rhrk.uni-kl.de majority gate device.For the simulations, the material parameters of 100 nm-thick Yttrium-Iron-Garnet (

We investigate yttrium iron garnet (YIG)/cobalt (Co) heterostructures using broadband ferromagnetic resonance (FMR). We observe an efficient excitation of perpendicular standing spin waves (PSSWs) in the YIG layer when the resonance frequencies of the YIG PSSWs and the Co FMR line coincide. Avoided crossings of YIG PSSWs and the Co FMR line are found and modeled using mutual spin pumping and exchange torques. The excitation of PSSWs is suppressed by a thin aluminum oxide (AlOx) interlayer but persists with a copper (Cu) interlayer, in agreement with the proposed model.

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...

We investigate the temperature dependent microwave absorption spectrum of an yttrium iron garnet sphere as a function of temperature (5 K to 300 K) and frequency (3 GHz to 43.5 GHz). At temperatures above 100 K, the magnetic resonance linewidth increases linearly with temperature and shows a Gilbert-like linear frequency dependence. At lower temperatures, the temperature dependence of the resonance linewidth at constant external magnetic fields exhibits a characteristic peak which coincides with a non-Gilbert-like frequency dependence. The complete temperature and frequency evolution of the linewidth can be modeled by the phenomenology of slowly relaxing rareearth impurities and either the Kasuya-LeCraw mechanism or the scattering with optical magnons. Furthermore, we extract the temperature dependence of the saturation magnetization, the magnetic anisotropy and the g-factor.arXiv:1703.09444v2 [cond-mat.mtrl-sci]

Abstract. Measurements of the exchange stiffness D and the exchange constant A of Yttrium Iron Garnet (YIG) films are presented. The YIG films with thicknesses from 0.9 µm to 2.6 µm were investigated with a microwave setup in a wide frequency range from 5 to 40 GHz. The measurements were performed when the external static magnetic field was applied in-plane and out-of-plane. The method of Schreiber and Frait [1], based on the analysis of the perpendicular standing spin wave (PSSW) mode frequency dependence on the applied out-of-plane magnetic field, was used to obtain the exchange stiffness D. This method was modified to avoid the influence of internal magnetic fields during the determination of the exchange stiffness. Furthermore, the method was adapted for in-plane measurements as well. The results obtained using all methods are compared and values of D between (5.18 ± 0.01) · 10 −17 T·m 2 and (5.34±0.02)·10 −17 T·m 2 were obtained for different thicknesses. From this the exchange constant was calculated to be A = (3.65 ± 0.38) pJ/m. arXiv:1408.5772v1 [cond-mat.mtrl-sci]