SGER: Microwave Induced Large Angle Magnetic Dynamics and Switching in Confined Structures

0827249_XiaoTECHNICAL：能够设计和制造具有可控磁化动力学和开关行为的磁性元件是磁性领域的最终目标。经过几十年的研究，线性响应假设成立的小角度进动动力学研究取得了一定的进展。大角度旋进和开关行为的磁化动力学仍然知之甚少，主要是由于缺乏实验技术，表征阻尼常数，磁化动力学和开关中的关键参数，在大角度旋进与选定的自旋波模式，更不用说它的关系，如形状和成分的结构特性。为了解决这些属性是必不可少的理解磁化动力学伴随着开关行为，导致高回报和变革性的研究。在此SGER中，PI将设计并实施一个灵敏的实验装置，以表征（1）具有稳定进动和明确定义的自旋波模式的可选大角度下的阻尼常数，（2）不同微波频率和功率下的磁化切换行为，以及（3）它们与结构特性的关系。该研究是高风险的性质，因为在设置灵敏度的严格要求，以表征纳米厚膜的亚微米尺寸。这一问题可能需要通过微波传输线沿着放置样品位置的迭代设计和建模来解决。非技术性：除了在科学上理解伴随着切换的磁化动力学方面的高回报外，高风险的承诺将对记录行业产生重大影响，这些行业正在寻找解决方案，以满足日益增长的存储密度需求，这些需求已经超过了基本的物理极限。该研究提供了微波辅助磁化动力学，解决了磁存储位的小切换场和长期热稳定性的矛盾要求。该设置还可以扩展到包含可以显著增强其当前不存在的能力的其他现有技术。最后，微波和自旋极化输运测量的结合可能会导致新的现象和新类型的设备，这是以前不可能的。考虑到自旋电子学和微波领域的广泛应用，这样的前提是非常诱人的。在这方面，培养具有微波，磁化和理论模型专业知识的研究生是非常可取的，并将在本提案中实现。关键词：磁化动力学，磁化翻转，微波，微波辅助翻转，磁畴，铁磁共振，大角度进动

0827249_XiaoTECHNICAL: To be able to design and fabricate magnetic elements with controllable magnetization dynamics and switching behaviors are an ultimate goal in the field of magnetism. Through decades of research, progress has been made in dynamics with small angle precession where the assumption of linear response is valid. Magnetization dynamics with large angle precession and switching behaviors remain to be poorly understood, mainly due to the lack of experiment techniques that characterize the damping constant, a critical parameter in magnetization dynamics and switching, at large angle precession with selected spin wave mode, let alone its relationship to structural properties such as shape and composition. To address these properties are essential to understanding the magnetization dynamics accompanied with switching behaviors, leading to high payoff and transformative research. In this SGER, PI will design and implement a sensitive experimental setup to characterize (1) the damping constant at selectable large angle with stable precession and with well defined spin wave modes, (2) magnetization switching behaviors in presence of different microwave frequency and power, and (3) their relationships with structural properties. The research is high risk in nature because of the stringent requirements in the set up sensitivity in order to characterize nanometer thick films of submicron size. The problem may have to be solved by iterative designing and modeling of microwave transmission line along with sample position placement. NON-TECHNICAL: In addition to the high pay-off in scientific understanding of magnetization dynamics accompanied with switching, the high risk undertaking will significantly impact on the recording industries, which are searching for solutions to meet ever increasing storage density demands that have exceeded fundamental physics limits. The research offers microwave assisted magnetization dynamics, solving the conflicting requirements of a small switching field and a long term thermal stability of a magnetic storage bit. The setup can also be expanded to incorporate other existing techniques that can significantly enhance its capability that do not exist currently. Finally, the combination of microwave and spin polarized transport measurements could potentially lead to new phenomena and new types of devices that was not possible before. Such a premise is extremely enticing considering the broad applications in both spintronics and microwave fields. In this regard, training graduate students with expertise in microwave, magnetization, and theoretical model are highly desirable and will be achieved in this proposal. Key words: Magnetization dynamics, magnetization switching, microwave, microwavewave assisted switching, magnetic domain, ferromagnetic resonance, large angleprecession