Sum-frequency excitation of coherent magnons

Coherent excitation of magnons is conventionally achieved through Raman scattering processes, in which the difference-frequency components of the driving field are resonant with the magnon energy. Here, we describe mechanisms by which the sum-frequency components of the driving field can be used to coherently excite magnons through two-particle absorption processes. We use the Landau-Lifshitz-Gilbert formalism to compare the spin-precession amplitudes that different types of impulsive stimulated and ionic Raman scattering processes and their sum-frequency counterparts induce in an antiferromagnetic model system. We show that sum-frequency mechanisms enabled by linearly polarized driving fields yield excitation efficiencies comparable or larger than established Raman techniques, while elliptical polarizations produce only weak and circular polarizations no sum-frequency components at all. The mechanisms presented here complete the map for dynamical spin control by means of Raman-type processes.

Automated summary

The study explores mechanisms for coherent excitation of magnons through sum-frequency components of the driving field, showing that efficiencies comparable or higher than established Raman techniques can be achieved using linearly polarized driving fields. Elliptical polarizations, on the other hand, produce weaker effects.