Magnonics in view of applications in logic

In the talk, I will concentrate exclusively on magnon-based processing of digital data. The idea to code binary data into spin-wave amplitude was first stated. It was proposed to use a Mach-Zehnder spin-wave interferometer equipped with current-controlled phase shifters embedded in the interferometer arms to construct logic gates. The drawback of these logic gates is that it is impossible to combine even two logic gates without additional magnon-to-voltage converters. This fact stimulates the search for means to control a magnon current with another. Recently, we have demonstrated that such control is possible due to nonlinear magnon scattering, and a magnon transistor was realized. The proof of concept device was fabricated from the electrically insulating magnetic material yttrium-iron-garnet (YIG) in order to decouple data processing from the electron system. In this three-terminal device, the density of the magnon current flowing from the Source to the Drain (see blue spheres in the figure) is controlled by the magnons injected into the Gate of the transistor (red spheres). The magnonic crystal in the form of an array of surface grooves is used to increase the density of the gate magnons and, consequently, to enhance the efficiency of nonlinear four-magnon scattering. It was shown that the Gate-to-Drain magnon current can be decreased up to three orders of magnitude. The potential for the miniaturization of this transistor will be discussed.