Spin Wave Based Computing: Promises and Hurdles on the Road

In this presentation we provide an overview of recent efforts to develop computing systems based on spin waves instead of charges and voltages. Note that Spin-wave computing can be considered a subfield of spintronics, which uses magnetic excitations for computation and memory applications. We start with an introduction to magnetic interactions, spin-wave physics, and basic spin-wave computing mechanisms. Subsequently, we review individual spin-wave devices while focusing on spin-wave majority gates as they are the most prominently pursued spin-wave device concept. Afterwards, we discuss the current status and the challenges to combine spin-wave gates to obtain circuits and ultimately computing systems, by considering essential aspects, e.g., gate interconnection, logic level restoration, input-output consistency, and fan-out achievement. Then, we argue that spin-wave circuits need to be embedded into conventional complementary metal-oxide-semiconductor (CMOS) circuits to obtain complete functional hybrid computing systems, review the state of the art of benchmarking such hybrid spin-wave-CMOS systems, and discuss challenges towards their practical realization. The benchmark indicates that hybrid spin-wave-CMOS systems promise ultralow-power operation and may ultimately outperform conventional CMOS circuits in terms of the power-delay-area product.