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

由于损耗低，六方晶系铁氧体是用于高频通信设备和雷达的首选磁性材料。 然而，这种设备的主要缺点是需要磁场源来调谐需要非常高功率的工作频率。 这样的调谐也使得它们体积庞大并且不兼容于与半导体器件的集成。 该项目旨在开发新一代铁氧体磁性器件，通过施加电压可调谐，因此可以小型化并与半导体电子器件集成。 该项目的动机是最近的报告之间的强相互作用的磁性有序的铁氧体和电场所产生的施加电压，导致电压控制的磁参数。 拟议的研究的主要任务是生长高质量的薄膜和单晶的六角铁氧体，磁序和电场之间的相互作用的性质的研究，以及铁氧体滤波器和谐振器的设计，制造和表征用于感兴趣的频段的消费电子产品和系统的重要性，为国防。 该研究的更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。 高中三年级和四年级学生，特别是妇女和少数民族，将从当地学校招募，以促进参与研究。提出了M型六方晶系铁氧体非线性磁电相互作用和磁场控制的研究方案。 其动机是最近发现的现象，在单晶薄膜的锶六角铁氧体（SrM）。 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）调谐。 计划研究单晶片和薄膜的纯，（钴，钛）和（钴，锡）取代钡和锶六角铁氧体。 这些系统具有单轴各向异性场Ha = 4-20 kOe，FMR在10-50 GHz的频率范围内。 单晶是手头上和薄膜将生长液相外延（LPE）的各种基板上，包括氧化镁和蓝宝石。 对非线性微流体效应的研究是通过观察和调谐直流、正弦和脉冲电场下的多畴和单畴状态下的铁磁共振来完成的。关于FMR的E调谐的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性。拟议的研究的一个重要组成部分是六角铁氧体谐振器和带阻和带通滤波器的设计，用于在10-50 GHz和表征方面的E-调谐和设备的品质因数。将探讨提高器件可调谐性和品质因数以及减少电力需求的途径。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.