Spin Wave Electromagnetic Nano‐Antenna Enabled by Tripartite Phonon‐Magnon‐Photon Coupling. Issue 8 (19th January 2022)

• Record Type: Journal Article
• Authors: Fabiha, Raisa; Lundquist, Jonathan; Majumder, Sudip; Topsakal, Erdem; Barman, Anjan; Bandyopadhyay, Supriyo
• Is Part Of: Advanced science. Volume 9:Issue 8(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-01-19
• Subjects: acoustic waves -- electromagnetic waves -- nano‐antenna -- spin waves -- tripartite coupling; Science -- Periodicals; 505
• DOI: 10.1002/advs.202104644
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: Tripartite coupling between phonons, magnons, and photons in a periodic array of elliptical magnetostrictive nanomagnets delineated on a piezoelectric substrate to form a 2D two‐phase multiferroic crystal is investigated. Surface acoustic waves (SAW) (phonons) of 5–35 GHz frequency launched into the substrate cause the magnetizations of the nanomagnets to precess at the frequency of the wave, giving rise to confined spin‐wave modes (magnons) within the nanomagnets. The spin waves, in turn, radiate electromagnetic waves (photons) into the surrounding space at the SAW frequency. Here, the phonons couple into magnons, which then couple into photons. This tripartite phonon‐magnon‐photon coupling is thus exploited to implement an extreme sub‐wavelength electromagnetic antenna whose measured radiation efficiency and antenna gain exceed the approximate theoretical limits for traditional antennas of the same dimensions by more than two orders of magnitude at some frequencies. Micro‐magnetic simulations are in excellent agreement with experimental observations and provide insight into the spin‐wave modes that couple into radiating electromagnetic modes to implement the antenna. Abstract : Tripartite phonon‐magnon‐photon coupling in a 2D array of two‐phase multiferroic nanomagnets implements a novel ultra‐sub‐wavelength electromagnetic antenna whose gain and radiation efficiency exceed the theoretical limits for traditional antennas of the same dimensions by many orders of magnitude at some (≈GHz) frequencies. Surface acoustic waves (phonons) excite confined spin waves (magnons) in the nanomagnets which radiate electromagnetic waves (photons) into the surrounding medium.