EAGER: Spintronic extreme sub-wavelength and super-gain active electronically scanned antenna (AESA) enabled by phonon-magnon-plasmon-photon coupling.

传统天线的一个严重缺点是，当它们被制造得比它们所发射的电磁辐射的波长小得多时，它们的效率会直线下降。这是制造超小型天线的一个障碍，这种天线可以在医学上植入病人体内，也可以嵌入隐形设备中用于防御或打击犯罪。这个障碍最近已经克服了一种新的类型的天线实现与磁致伸缩纳米磁铁建立在压电基板上。施加到衬底上的周期性电场周期性地使纳米磁体产生应变，这使得它们的磁化强度随时间振荡并发射电磁波。这种效应背后的现象是声子-磁振子-光子耦合。这些新型天线的效率超过传统天线效率的理论极限10万倍以上。目前的研究将引入一个额外的功能，通过耦合电荷振荡（称为等离子体）到天线通过修改它们的结构，这可以显着提高天线的性能。此外，通过操纵施加到衬底的周期性电场的方向，可以改变在衬底中传播的应变波的方向，这可以允许在空间中操纵辐射的电磁波束的能力，从而实现有源电子扫描天线（AESA）。这些天线将有可能开辟许多新的嵌入式应用，例如，医疗植入设备，与外部监视器通信，同时消耗极少量的能量，超小型隐形监听设备，个人通讯器和可穿戴电子产品。除了基础知识和技术影响外，拟议的研究还将通过培养在纳米制造，表征和测量以及器件模拟和设计方面接受过培训的研究生和本科生来造福社会。将特别关注创业机会，通过各种计划增加K-12和少数民族的参与，并通过流行的讲座和互联网博客教育公众。（二维人造多铁性晶体），可以产生一种新型的自旋电子电磁纳米-与相同尺寸的传统（电磁激励）天线相比，其增益和辐射效率超过几个数量级，达到理论极限。 低频发射到衬底中的（~100 MHz）表面声波（SAW）通过Villari效应激发纳米磁体中的磁化旋进，并且旋进磁化以SAW频率在周围介质中辐射电磁波，从而产生新型天线。另一方面，通过声子-磁振子耦合共振激发纳米磁体中的受限自旋波模式，然后这些自旋波通过磁振子-光子耦合以与SAW相同的频率将电磁波（光子）辐射到周围介质中。这构成了三重声子-磁振子-光子耦合。拟议的研究将通过将表面等离子体激元引入模式混合来研究四路声子-等离子体激元-磁振子-光子耦合来扩展概念，这有望提高从声子到等离子体激元到磁振子到光子的模式转换效率，从而增强天线性能。另外，已经观察到，如果SAW传播的方向相对于纳米磁体的易磁化轴改变，则天线辐射图案改变。该项目的目标是利用这一功能，通过改变声表面波传播方向来电子引导辐射波束，以实现有源电子扫描天线（AESA）。该奖项反映了NSF的法定使命，并且通过使用基金会的知识价值和更广泛的影响力审查标准进行评估，被认为值得支持。

A serious shortcoming of conventional antennas is that their efficiencies plummet when they are made much smaller than the wavelength of the electromagnetic radiation they transmit. This is an impediment to building ultra-small antennas that can be medically implanted in a patient or embedded in a stealth device for defense or crime-fighting. This roadblock has been recently overcome by a novel genre of antennas implemented with magnetostrictive nanomagnets built on a piezoelectric substrate. A periodic electric field applied to the substrate periodically strains the nanomagnets, which makes their magnetizations oscillate in time and emit electromagnetic waves. The phenomenon that underlies this effect is phonon-magnon-photon coupling. The efficiencies of these novel antennas were found to exceed the theoretical limits on the efficiencies of traditional antennas by more than 100,000 times. The present research will introduce an additional feature by coupling electric charge oscillations (called plasmons) into the antennas by modifying their structure, which can significantly improve the antenna performance. Moreover, by manipulating the direction of the periodic electric field applied to the substrate, the direction of the strain wave propagating in the substrate can be changed, which may allow capability to steer the radiated electromagnetic beam in space, thereby implementing an active electronically scanned antenna (AESA). These antennas will have the potential to open up many new embedded applications, e.g., medically implanted devices that communicate with external monitors while consuming miniscule amounts of energy, ultra-small stealthy listening devices, personal communicators and wearable electronics. Apart from the fundamental knowledge and technological impact the proposed research will benefit society by producing graduate and undergraduate students trained in nanofabrication, characterization and measurement, as well as in device simulation and design. Particular attention will be paid to entrepreneurship opportunities, increasing K-12 and minority participation through various programs, and educating public through popular lectures and internet blogs.Recently it has been demonstrated in the PI’s group that periodic arrays of magnetostrictive nanomagnets deposited on a piezoelectric substrate (a two-dimensional artificial multiferroic crystal), can generate a novel genre of spintronic electromagnetic nano-antennas whose gain and radiation efficiency exceed by several orders of magnitude reaching theoretical limits as compared to traditional (electromagnetically actuated) antennas of the same dimensions. A low frequency (~100 MHZ) surface acoustic wave (SAW) launched into the substrate excites magnetization precession in the nanomagnets via the Villari effect and the precessing magnetization radiates electromagnetic waves in the surrounding medium at the SAW frequency, thereby resulting a novel antenna A high frequency (~10 GHz) SAW, on the other hand, resonantly excites confined spin wave modes in the nanomagnet via phonon-magnon coupling and these spin waves then radiate electromagnetic waves (photons) into the surrounding medium via magnon-photon coupling at the same frequency as the SAW. This constituted tripartite phonon-magnon-photon coupling. The proposed research will extend the concept by introducing surface plasmons into the mode mixing to study four-way phonon-plasmon-magnon-photon coupling which is expected to enhance the mode conversion efficiency from phonons to plasmons to magnons to photons, thereby enhancing antenna properties. Additionally, it has been observed that the antenna radiation pattern changes if the direction of SAW propagation changes with respect to the easy axes of the nanomagnets. The goal of this project is to exploit this feature to electronically steer the radiated beam by changing the direction of SAW propagation in an effort to implement an active electronically scanned antenna (AESA).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.