  An optical frequency comb consists of a set of discrete and equally spaced
frequencies and has found wide applications in the synthesis over broad
spectral frequencies of electromagnetic wave and precise optical frequency
metrology. Despite the analogies between magnons and photons in many aspects,
the analogue of optical frequency comb in magnonic system has not been
reported. Here, we theoretically study the magnon-skyrmion interaction and find
that magnonic frequency comb (MFC) can be generated above a threshold of
driving amplitude, where the nonlinear scattering process involving three
magnons prevails. The mode-spacing of the MFC is equal to the breathing-mode
frequency of skyrmion and is thus tunable by either electric or magnetic means.
The theoretical prediction is verified by micromagnetic simulations and the
essential physics can be generalized to a large class of magnetic solitons. Our
findings open a new pathway to observe the frequency comb structure in magnonic
devices, that may inspire the study of fundamental nonlinear physics in
spintronic platform in the future.
