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陷是，当它们被制造得比它们发射的电磁辐射的波长小得多时，它们的效率会直线下降。这是建造超小型天线的障碍，这些天线可以通过医学手段植入患者体内，也可以嵌入用于防御或打击犯罪的隐形设备中。这一障碍最近被一种新型的天线克服了，这种天线是用建立在压电衬底上的磁致伸缩纳米磁网实现的。施加在衬底上的周期性电场周期性地拉动纳米磁铁，使它们的磁化及时振荡并发射电磁波。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被发现比传统天线的效率理论极限高出100,000倍以上。本研究将通过改变天线的结构，将电荷振荡(称为等离子体激子)耦合到天线中，从而显著提高天线的性能。此外，通过操纵施加到基板上的周期性电场的方向，可以改变在基板中传播的应变波的方向，这可以允许在空间中引导辐射的电磁束，从而实现有源电子扫描天线(AESA)。这些天线将有可能打开许多新的嵌入式应用，例如，医疗植入设备，在消耗极少量能量的同时与外部监视器通信，超小型隐形监听设备，个人通信器和可穿戴电子设备。除了基础知识和技术影响外，拟议的研究还将通过培养接受纳米制造、表征和测量以及设备模拟和设计方面的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和少数群体的参与，并通过流行讲座和互联网博客教育公众。最近，Pi的小组证明，在压电基板(二维人造多铁晶体)上沉积周期性磁致伸缩纳米磁体阵列，可以产生一种新型的自旋电子电磁纳米天线，其增益和辐射效率比相同尺寸的传统(电磁驱动)天线高出几个数量级，达到理论极限。发射到衬底中的低频(~100 MHz)声表面波(SAW)通过Villari效应激发纳米磁体中的磁化进动，并在SAW频率处辐射周围介质中的电磁波，从而形成一种新型天线A高频(~10 GHz)SAW，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，这些自旋波然后以与SAW相同的频率通过磁非光子耦合向周围介质辐射电磁波(光子)。这就构成了三方声子-磁振子-光子耦合。该研究将通过将表面等离子体引入模式混频来扩展这一概念，研究声子-等离子体-磁振子的四向耦合，有望提高从声子到等离子体到磁子到光子的模式转换效率，从而提高天线的性能。此外，已经观察到，如果声表面波传播方向相对于纳米磁体的易轴改变，则天线辐射方向图改变。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，努力实现有源电子扫描天线(AESA)。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，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.