GOALI: Spin-Transfer in Magnetic Nanostructures

*技术摘要*这个NSF-GOALI项目汇集了来自纽约大学和IBM的纳米磁学领域的领先研究人员，目的是加深对自旋转移物理的理解，并将自旋转移应用于高性能设备。自旋转移是一种机制，通过它，自旋极化的电流可以反转纳米磁铁的磁取向，并诱导诸如自旋波的磁激发。这是一项令人兴奋的发展，很可能使磁性信息处理和存储方面的显著改进成为可能。这是因为自旋转移提供了一种机制，可以快速逆转具有大磁各向异性的纳米磁铁的磁化，否则需要巨大的局部磁场--这是提高磁信息存储密度的关键成就。然而，随着纳米磁体尺寸的减小，由于与热和电噪声相关的随机力的作用，它们的磁矩变得更容易发生反转。因此，理解噪声对自旋转移驱动的磁化动力学的影响是至关重要的。这个项目将通过对由自旋电流激发的单个纳米磁体的实验研究来促进对自旋转移物理的理解，包括一个新的研究方向，将使用通过激励铁磁绝缘体产生的自旋电流。这些实验研究将协同进行，并以存在自旋转移力矩的噪声诱导相变的理论分析为指导。理论分析将集中在非梯度确定性动力学与随机力相互作用所产生的新现象。参与这项合作的研究生和本科生将从学术界和产业界的互动中受益。*非技术摘要*该项目汇集了来自纽约大学和IBM的顶尖研究人员，目的是促进对纳米级磁性设备和材料的理解和应用。磁性纳米结构在技术上得到了广泛的应用，其中最先进的应用是信息处理。这在美国是一个巨大的行业，随着全球对数据处理和存储的需求不断增加，该行业正在迅速增长。人们已经发现，在微型磁性设备中，直流电可以通过一种称为自旋转移的机制来改变磁化方向。这是一个令人兴奋的发展，可能会使磁信息处理和存储方面的显著改进成为可能。这个项目将通过使用独特的高频测量技术研究由自旋电流激发的单个磁性纳米结构，来解决关于电流和磁化之间相互作用的性质的重要和基本的问题。这项研究将与这一磁学研究前沿领域的青年科学家的培训相结合。参与的研究生和本科生将从学术界和产业界的互动以及纽约大学和IBM之间的交流中受益。他们的教育将通过接触到工业环境中存在的各种观点、专业知识和技术而得到丰富。高中生也将参与这项研究。

****Technical Abstract****This NSF-GOALI project brings together leading researchers in nanomagnetism from New York University and IBM with the aim of furthering the understanding of the physics of spin-transfer and applications of spin-transfer to high performance devices. Spin-transfer is a mechanism by which a spin-polarized current can reverse the magnetic orientation of a nanomagnet and induce magnetic excitations such as spin-waves. This is an exciting development that will very likely enable dramatic improvements in magnetic information processing and storage. This is because spin-transfer offers a mechanism for rapidly reversing the magnetization of nanomagnets with large magnetic anisotropy that would otherwise require huge local magnetic fields -an achievement critical to increasing magnetic information storage density. However, as nanomagnets are reduced in size their magnetic moments become more susceptible to reversal due to random forces associated with thermal and electrical noise. An understanding of the effects of noise on spin-transfer driven magnetization dynamics is thus critical. This project will advance understanding of spin-transfer physics through experimental studies of individual nanomagnets excited by spin-currents, including a new research direction that will use spin-currents generated through excitation of ferromagnetic insulators. These experimental studies will be conducted in concert and guided by a theoretical analysis of noise-induced transitions in the presence of spin-transfer torques. The theoretical analysis will focus on new phenomena generated by the interaction of a nongradient deterministic dynamics with random forces. Graduate and undergraduate students involved in this collaboration will gain by interactions between academia and industry.****Non-Technical Abstract****This project brings together leading researchers from New York University and IBM with the aim of furthering the understanding and application of nanometer scale magnetic devices and materials. Magnetic nanostructures are widely used in technology with the most advanced applications found in information processing. This is a huge industry in the United States that is growing rapidly, with the ever-increasing worldwide demands for data processing and storage. It has been discovered that in miniature magnetic devices a direct electrical current can switch the direction of magnetization by a mechanism known as spin-transfer. This is an exciting development that may enable dramatic improvements in magnetic information processing and storage. There are important and fundamental questions about the nature of the interaction between the current and magnetization that this project will address through studies of individual magnetic nanostructures excited by spin-currents using unique high frequency measurement techniques. This research will be integrated with the training of young scientists in this forefront area of magnetism research. Participating graduate and undergraduate students will gain by interactions between academia and industry and through exchanges between NYU and IBM. Their education will be enriched through exposure to a variety of perspectives, expertise and techniques present in an industrial setting. High school students will also participate in this research.