Generation of Microwaves With Tuneable Frequencies in Ultracompact 'Magnon Microwave Antenna' via Phonon-Magnon-Photon Coupling

Here, we report a 'magnon microwave antenna' (MMA) for the generation of microwaves with tuneable frequencies, based on modulation of confined spin waves (SWs) in the patterned array of magnetostrictive nanomagnets/piezoelectric heterostructures caused by the surface acoustic waves (SAWs). A SAW launched on a piezoelectric substrate produces a periodic strain within the nanomagnets patterned on it, which, in turn, stimulates magnetization precession resulting in different magneto-dynamical resonance modes in the array of nanomagnets with a rich SW texture. The generated SWs (magnons) further interact with the EM radiation (photons) at the SAW frequency. The phonon-magnon-photon coupling in the patterned array of nanowires (NWs) generates a 0.56 GHz microwave frequency with a 13.9 MHz linewidth and a Q-factor of 40, while that in a matrix of nanodots (having same overall area) provides tuneable frequencies leading up to 30 GHz with a linewidth of 59.1 MHz and an enhanced Q-factor of 439; having nonvolatile spin textures in both the cases. The generated nonvolatile spin textures of the NWs/nanodots can also be useful in energy-efficient logic and low-power computing applications.