Unidirectional propagation of spin waves excited by femtosecond laser pulses in a planar waveguide

Low-energy magnonic logic circuits are an actively developing field of modern magnetism. The potential benefits of magnonics for data processing are vitally dependent on units based on non-reciprocal propagation of spin waves in analogy to semiconductor diodes and transistors in electronics. In this article, we suggest the approach to realize non-reciprocal propagation of spin waves in a ferromagnetic metallic waveguide by exciting them with femtosecond laser pulse. Using micromagnetic modeling, we show that the combination of an external magnetic field and the position of the excitation laser spot across the waveguide leads to unidirectional propagation of the excited spin-wave packet. The results are crucial for the design of hybrid magnonic-photonic circuits in future generations of data processing devices.
Comment: 9 pages, 6 figures, 2 supplementary files. The .pdf file: details of simulation, static magnetisation distribution, and waves propagation. The .gif file: evolution of out-of-plane magnetization component distribution of the entire waveguide area at excitation with pulses focused into a round spot. The value of the external magnetic field is 17 mT, the excitation area center position is -1.2 um