Experimental prototype of a spin-wave majority gate

Featuring low heat dissipation, devices based on spin-wave logic gates promise to comply with increasing future requirements in information processing. In this work, we present the experimental present Researchers have created an experimental realization of a majority gate based on the interference of spin waves in an Yttrium-Iron-Garnet-based waveguiding structure. This logic device features a three-input combiner with the logic information encoded in a phase of 0 or π of the input spin waves. We show that the phase of the output signal represents the majority of the three phase states of the spin waves in the three inputs. A switching time of about 10 ns in the prototype device provides evidence for the ability of sub-nanosecond data processing in future down-scaled devices.

This first device prototype, though physically larger than what Fischer and his colleagues see for eventual large-scale use, clearly demonstrates the applicability of spin-wave phenomena for reliable information processing at GHz frequencies.

The brass block serves as an electric ground plate ensuring an efficient insertion of the RF currents to the antennae and, on the other hand, microwave connectors mounted to the block allow for the embedding of the device into our microwave setup. Credit: Fischer/Kewenig/Meyer

The scaling of conventional CMOS-based nanoelectronics is expected to become increasingly intrinsically limited in the next decade. Therefore, novel beyond-CMOS devices are being actively developed as a complement to expand functionally in future nanoelectronic technology nodes. In particular, the field of magnonics which utilizes the fundamental excitations of a magnetic system—spin waves and their quanta—magnons as data carriers, provides promising approaches to overcome crucial limitations of CMOS since they may provide ultralow power operation and nonvolatility. Magnonic devices are especially amenable to building majority gates with excellent scaling potential, leading to an improved circuit efficiency. Hence, majority gates can be considered to be key devices in a novel approach to circuit design with a strongly improved area and power scaling behavior.

Spin waves cover characteristic frequencies in the GHz regime, and their wavelength can easily be reduced down to the nanometer range. Furthermore, their dispersion relation is highly versatile depending on the material parameters, as well as magnetization and field configuration,8 making them usable in a wide range of devices. In this context, majority gates are of special interest since a simple spin-wave combiner substitutes several tens of transistors, and three majority gates suffice for creating a full-adder. Multi-frequency operation allows for parallel data processing.

In this work, they present the experimental realization and investigation of a prototype of a spin-wave majority gate, whose functionality and performance on the microscopic scale have been investigated in numerical simulations. The investigated majority gate has three inputs and one output.


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