We demonstrate the functionality of spin-wave logic XNOR and NAND gates based on a MachZehnder type interferometer which has arms implemented as sections of ferrite film spin-wave waveguides. Logical input signals are applied to the gates by varying either the phase or the amplitude of the spin waves in the interferometer arms. This phase or amplitude variation is produced by Oersted fields of dc current pulses through conductors placed on the surface of the magnetic films.Although commonly used for data storage applications, there have been relatively few attempts to employ magnetic phenomena for performing logical operations. The suggested concepts include the control of domain wall movement [1], of magnetoresistance of individual magnetic elements [2], and of a magnetostatic field of a set of magnetic nanoelements [3]. Yet another concept is using spin-wave interferometers. It was discussed theoretically in Refs. [4,5,6], but there was only one experimental demonstration of spin wave logic gate functionality [7], where an one-input NOT gate was implemented in a interferometer-like geometry. In the present work we experimentally demonstrate the functionality of more complicated logic gates based on spin waves.The fabricated prototype of a XNOR logic gate is a direct extension of the NOT gate from Ref. [7] which was based on a Mach-Zehnder interferometer. For its implementation the reference interferometer arm of the NOT gate is replaced by an arm identical to the signal arm. Controlling phases accumulated by the spin waves in both arms allows one to perform the XNOR operation.Demonstrating the functionality of a NAND logic gate is a considerable step forward in the development of spin wave logic compared to the NOT and XNOR gates. Firstly because the NAND function belongs to a class of universal functions which means that combining NAND gates allows one to construct gates of other types. Secondly because for its implementation, we use here a new physical principle: direct control of spin wave amplitudes in the interferometer arms.Figure 1(b) shows the principle setup of an exclusive not OR (XNOR, also called logical equality) gate. It consists of two arms of a spin-wave Mach-Zehnder interferometer implemented as ferrite film structures. Spin waves are inserted in both arms using microstrip antennas connected to a common microwave pulse source, thus guaranteeing the same phase in both arms. The spin waves are phase-coherently detected using microstrip antenna detectors. The signals of both arms are brought to interference electronically. The phase accumulated by the spin waves on their paths through the two arms is controlled by applying dc currents I 1 and I 2 to the arms. Figure 1(a) shows phase inserted due to a current in an interferometer arm. One sees a linear dependence of the accumulated phase on the current. One also sees that the phase characteristics in both arms are identical.The currents I 1 and I 2 serve as logical inputs, where a logical zero is represented by I = 0 A and a logical one by the cur...

Theoretical constructs of logical gates implemented with plant roots are morphological computing asynchronous devices. Values of Boolean variables are represented by plant roots. A presence of a plant root at a given site symbolises the logical True, an absence the logical False. Logical functions are calculated via interaction between roots. Two types of two-inputs-two-outputs gates are proposed: a gate x, y → xy, x + y where root apexes are guided by gravity and a gate x, y → xy, x where root apexes are guided by humidity. We propose a design of binary half-adder based on the gates.

We found by micromagnetic simulations that the motion of a transverse wall (TW) type domain wall in magnetic thin-film nanostripes can be manipulated via interaction with spin waves (SWs) propagating through the TW. The velocity of the TW motion can be controlled by changes of the frequency and amplitude of the propagating SWs. Moreover, the TW motion is efficiently driven by specific SW frequencies that coincide with the resonant frequencies of the local modes existing inside the TW structure. The use of propagating SWs, whose frequencies are tuned to those of the intrinsic TW modes, is an alternative approach for controlling TW motion in nanostripes.

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 present an experimental study of spin-wave excitation and propagation in microstructured waveguides patterned from a 100 nm thick yttrium iron garnet (YIG)/platinum (Pt) bilayer. The life time of the spin waves is found to be more than an order of magnitude higher than in comparably sized metallic structures despite the fact that the Pt capping enhances the Gilbert damping. Utilizing microfocus Brillouin light scattering spectroscopy, we reveal the spin-wave mode structure for different excitation frequencies. An exponential spin-wave amplitude decay length of 31 µm is observed which is a significant step towards low damping, insulator based micro-magnonics.

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...

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Since the direct observation of magnetization reversal processes in nanostructured systems is hard to achieve, we use magnetoresistance measurements as an indirect sensing tool. To avoid dipolar interactions present in nanowire gratings individual Co nanowires are prepared by electron beam lithography on Si substrates. Using a special two step process nonmagnetic gold contacts are attached to the Co nanowires to exclude an influence of the contact structures on the magnetization reversal process. To support the magnetoresistance analysis also the structure and morphology as well as the magnetic properties of the Co nanowires have been characterized using various microscopy and measurement techniques. Depending on the direction of the applied field three different magnetoresistance measurements can be distinguished. Based on the anisotropic magnetoresistance effect the transversal and the polar magnetoresistance reflect a coherent rotation of the magnetization independent of the wire width. In contrast, the longitudinal magnetoresistance shows a wire widths dependence of the magnetization reversal processes. In small wires nucleation processes occur whereas in wide wires the formation of complex domain structures has been observed. Nanowires with a width in between these groups show "transition"-like reversal processes.