Direct Imaging of High‐Frequency Multimode Spin Wave Propagation in Cobalt‐Iron Waveguides Using X‐Ray Microscopy beyond 10 GHz

Abstract

The rising research field of magnonics, which is named after the quanta of spin waves, represents a potential candidate for substituting electronic devices as information carriers at the nanoscale. [1-5] Nevertheless, data communication does not represent the only prospective route for magnonics. High-frequency radar systems get increasingly important, e.g., for autonomous driving. This requires very accurate and fast position tracking as well as communication with surrounding vehicles. [6] However, complex electronic building blocks for radar transceivers are vulnerable for nonlinearities at high frequencies and, thus, cause serious problems regarding reliable detection and communication. [6-9] With respect to higher stability, higher data throughput, and faster logic operations at frequencies above 10 GHz, magnonic circuits represent a very promising approach, which allows for substituting several electronic elements in current radar systems. [10] Radar sensors typically require a larger signal bandwidth than communication signals. Thus, high performance in both radar and communication applications requires fine-tuning of signals and advanced bandwidth concepts. Therefore, single-and multi-carrier waveforms between 20 and 30 GHz are very promising for increasing transmission rates and combining communication and sensing. [6] To this end, magnonic waveguides show outstanding characteristics for reliable multimode propagation, [11-14] which could define the backbone of magnonic building blocks in prospective radar applications. [3,15] In this work, we demonstrate the spatially and temporally resolved observation of spin wave excitation and propagation in such magnonic cobalt-iron (CoFe) waveguides at the nanoscale by time-resolved scanning transmission X-ray microscopy (STXM). The large saturation magnetization of CoFe results

Propagation of Spin Waves in a 2D Vortex Network

“…Spin waves, also named as magnons, are elementary excitations of electronic spins in magnetic materials. − Spin waves can be used as information carriers to transmit signals in nanomagnonic logic and signal process devices, covering a wide frequency range from a few hundred MHz to several THz, with the wavelength from micrometers to nanometers. − The advantages of applying spin wave to devices include the low power due to the reduction of Joule heating, and the device miniaturization owing to the shortening of wavelength in the submicrometer range. − …”