Voltage-Tunable High-Frequency Ferrite Devices based on Non-Linear Magnetoelectric Interactions

由于损耗低，六方铁氧体是高频通信设备和雷达中首选的磁性材料。然而，这种设备的主要缺点是需要一个磁场源来调节工作频率，这需要非常高的功率。这种调整也使它们体积庞大，无法与半导体设备集成。该项目旨在通过施加电压可调谐的新一代铁氧体磁性器件，因此可以小型化并与半导体电子集成。该项目的动机是最近有报道称，铁氧体中的磁有序与外加电压产生的电场之间存在强相互作用，从而导致磁参数的电压控制。该研究的主要任务是培养高质量的六方铁氧体薄膜和单晶，研究磁序和电场之间相互作用的性质，设计、制造和表征铁氧体滤波器和谐振器，用于消费电子产品和国防重要系统的感兴趣的频段。本研究的广泛影响包括为本科生和研究生提供先进材料合成和测量技术的研究培训以及为高中生提供研究经验。将从当地学校招募初中生和高中生，特别是妇女和少数民族，以促进参与研究。提出了m型六方铁氧体非线性磁电相互作用及磁场控制的研究方案。其动机是最近在六铁体锶（SrM）单晶薄膜中发现了这种现象。在静电场E作用下，SrM厚膜中的ME相互作用导致磁序参数的变化，表现为铁磁共振（FMR）的调谐。计划研究纯的单晶片和薄膜，以及（Co, Ti）和（Co,Sn）取代Ba和Sr六铁体。这些系统具有单轴各向异性场Ha = 4-20 kOe， FMR频率范围为10-50 GHz。单晶和薄膜将通过液相外延（LPE）生长在各种衬底上，包括氧化镁和蓝宝石。通过对直流、正弦和脉冲电磁场多域和单域状态下FMR的观察和调谐来研究NLME效应。FMR的e调谐数据将用于估计磁序参数和NLME耦合系数的变化及其对样品和输入电参数的依赖。提出的研究的一个重要组成部分是设计用于10-50 GHz的六铁氧体谐振器和带阻和带通滤波器，并在e调谐和器件性能方面进行表征。将探讨提高器件可调性和性能数字以及减少电力需求的途径。将开发非线性ME相互作用的模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Hexagonal ferrites are magnetic materials of choice for use in high frequency communication devices and radars due to low losses. The main drawback in such devices, however, is the need for a source of magnetic field to tune the operating frequency that requires very high power. Such tuning also makes them bulky and not compatible for integration with semiconductor devices. This project is aimed at a new generation of ferrite magnetic devices that are tunable by applying a voltage, and therefore, can be miniaturized and integrated with semiconductor electronics. The project is motivated by recent reports on strong interaction between the magnetic ordering in the ferrite and electric field generated by the applied voltage, resulting in voltage control of magnetic parameters. Primary tasks of the proposed research are to grow high quality thin films and single crystals of hexagonal ferrites, studies on the nature of interaction between magnetic order and electric field, and design, fabrication and characterization of ferrite filters and resonators for use in the frequency bands of interest for consumer electronics and systems of importance for the national defense. Broader impacts of the research include research training in advanced materials synthesis and measurement techniques for undergraduate and graduate students and research experience for high school students. High school juniors and seniors, women and minorities in particular, will be recruited from local schools to facilitate participation in research. A research program is proposed on non-linear magnetoelectric (NLME) interactions and electric field control of magnetism in M-type hexagonal ferrites. The motivation is the recent discovery of the phenomenon in single crystals films of strontium hexaferrite (SrM). Under a static electric field E, the ME interactions in a thick film of SrM resulted variation in the magnetic order parameters and manifested as tuning of ferromagnetic resonance (FMR). Studies are planned on single crystal platelets and thin films of pure, and (Co, Ti) and (Co,Sn) substituted Ba and Sr hexaferrites. These systems have uniaxial anisotropy fields Ha = 4-20 kOe with FMR in the frequency range 10-50 GHz. Single crystals are on hand and thin films will be grown by liquid phase epitaxy (LPE) on a variety of substrates including MgO and sapphire. Studies on NLME effects are to be done by observation and tuning of FMR under multi-domain and single domain states for DC, sinusoidal and pulsed E-fields. Data on E-tuning of FMR will be used to estimate variations in magnetic order parameters and NLME coupling coefficients and their dependence on sample and input electrical parameters. An important component of the proposed research is the design of hexaferrite resonators and band-stop and band-pass filters for use at 10-50 GHz and characterization in terms of E-tuning and device figures of merit. Avenues for enhancing device tunability and figures of merit and reduction of electric power requirements will be explored. Models will be developed for the non-linear ME interactions.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.