Frequency- and Amplitude Modulation of Spin-Wave Signals emitted from Topological Spin Textures

The investigation of spin-wave phenomena, dubbed magnonics, is an important branch of present magnetism research. This is in particular the case since spin waves are seen as promising signal carriers for future spintronic information and communication technology devices. For the excitation of spin waves with short wavelengths, it was typically necessary to either use patterned transducers with sizes on the order of the desired wavelengths (striplines or point-contacts) or to generate such spin waves parametrically by a spatially uniform double-frequency microwave signal. Recently, however, a new mechanism for the local excitation of spin waves has been found, which overcomes the lower wavelength limit given by the minimum patterning size. This method utilizes the translation of layered topological magnetic defects, i.e. the gyration of coupled spin vortex cores to generate propagating spin waves. In the present contribution we will show that a system similar to the one used in can be exploited to excite spin-wave signals with frequency- and amplitude modulation. With respect to a certain high-frequency spin-wave carrier signal, frequency and amplitude were periodically modulated encoding a lower frequency information signal. The resulting spin-wave dynamics was directly imaged by means of time-resolved scanning transmission x-ray microscopy. By demonstrating a very high agility for the vortex core based spin-wave generation mechanism, our findings further underline the potential applicability of this concept.