Microscopic nonlinear magnonic phase shifters based on ultrathin films of a magnetic insulator

Since magnonics takes advantage of not only the amplitude of spin waves but also their phase, tunable phase shifters are key elements for the implementation of magnonic circuits. Therefore, one of the major challenges in nano-magnonics is to find a physical mechanism to manipulate the spin-wave phase practically in simple and miniature devices. In this work, we experimentally demonstrate that intrinsic magnetic nonlinearities allow the implementation of efficient microscopic tunable phase shifters, where the phase is controlled by wave intensity. In the proposed devices, we achieve the tunability of the phase shift of more than 360° by a microwave power of few milliwatts over a propagation distance of about 10 μm. We show that the figure of merit of the demonstrated phase shifters is close to that of macroscopic devices based on alternative technologies. Our results also indicate that the ability to control the phase shift is primarily limited by nonlinear spin-wave damping and can be significantly improved by suppressing this effect. Our findings are important for the further development of integrated nano-magnonics for beyond-Moore computing.