Extreme Subwavelength Magnetoelastic Electromagnetic Antenna Implemented with Multiferroic Nanomagnets

Abstract

Antennas typically have emission/radiation efficiencies bounded by A/λ2(A < λ2) where A is the emitting area and λ is the emitted wavelength. That makes it challenging to miniaturize antennas to extreme subwavelength dimensions without severely compromising their efficiencies. To overcome this challenge, an electromagnetic (EM) antenna is actuated with a surface acoustic wave (SAW) whose wavelength is about five orders of magnitude smaller than the EM wavelength at the same frequency. This allows to implement an extreme subwavelength EM antenna, radiating an EM wave of wavelength λ = 2 m, whose emitting area is ≈10−8 m2 (A/λ2 = 2.5 × 10−9), and whose measured radiation efficiency exceeds the A/λ2 limit by over 105. The antenna consists of magnetostrictive nanomagnets deposited on a piezoelectric substrate. A SAW launched in the substrate with an alternating electrical voltage periodically strains the nanomagnets and rotates their magnetizations owing to the Villari effect. The oscillating magnetizations emit EM waves at the frequency of the SAW. These extreme subwavelength antennas that radiate with efficiencies a few orders of magnitude larger than the A/λ2 limit allow drastic miniaturization of communication systems.

Spin Wave Electromagnetic Nano‐Antenna Enabled by Tripartite Phonon‐Magnon‐Photon Coupling

“…In this work, we have demonstrated a novel magneto‐elastic antenna that radiates at microwave frequencies (> 3 GHz) and works on a principle that is completely different from the previous one in ref. [ 3 ]. Here, a SAW (phonons) generates confined spin waves in the magnetostrictive nanomagnets (magnons) which couple into radiative electromagnetic modes (photons).…”

“…SAWs of frequencies in the range of 1-30 GHz are launched in the LiNbO 3 substrate by applying 1 dbm (1 mW) of power from the microwave source between a pair of electrodes. As mentioned earlier, we choose two different pairs (3,4) and (5,7) in Figure 1(b), which would launch SAWs propagating in two different directions. We label the two cases as "orientation 1" and "orientation 2", respectively.…”

Applications of nanomagnets as dynamical systems: II

“…The edge-to-edge separation between the nanomagnets along the major axis is 45 nm and along the minor axis is 65 nm. Adapted from [74] with permission from Wiley.…”

Magnetization dynamics of nanoscale magnetic materials: A perspective

“…Another antenna miniaturization concept using unique fractal geometry has been proposed 330 . More recently, an antenna implemented with closely packed array of magnetostrictive nanomagnets deposited on a piezoelectric substrate has been developed 331 , where a SAW launched on the substrate with an alternating electrical voltage can periodically strain the nanomagnets and rotate their magnetizations owing to the Villari effect (Fig. 15 (a)).…”