Spin dynamics in magnetic nanostructures

电子的自旋而不是电荷在电子学中创造了非凡的机会，创造了自旋电子学。在这一领域的快速发展需要进一步的进展，在纳米几何形状的自旋相互作用的理解。我们的研究涉及自旋动力学，重点是研究纯自旋电流不伴有净电荷。*a）我们将继续研究非磁性金属层中的自旋电流输运，这些非磁性金属层在自旋电子学中起作用，作为磁源和磁阱终端之间的互连。特别是重金属薄膜，将放在一个大的自旋轨道相互作用，电子自旋相关，和高电阻率与空间电子局域化。重金属Pt、Ta和W金属薄膜在自旋电子学中具有重要的应用价值。它们具有非常大的自旋霍尔效应（SHE）和界面自旋轨道力矩（SOT），允许人们通过使用重金属中的电流来操作磁性随机存取存储器（MRAM）。在确定Pt、Ta和W中的自旋输运参数后，我们将研究自旋电流在Au/（Pt，Ta，W）界面处的反射。基于我们的PRL 2013，我们期望在Fe/Au/Pd，Pt，Ta，W异质结构中观察到由于Au层中自旋电流的空间限制而导致的量子阱态。 这是基础物理学，因为量子阱态是典型的可逆过程，而自旋泵是不可逆过程。 重金属也将用于自旋扭矩驱动的纳米柱器件，旨在进一步了解界面SOT和自旋损耗存储器的作用，从而改进磁性随机存取存储器（MRAM）架构。*B）大的自旋电流可以通过在铁磁体/正常金属界面处使用磁矩的大的旋进角来实现。事实上，这可以导致在自旋扭矩装置中使用自旋极化净电荷电流的可比较的自旋电流。钇铁石榴石（YIG）薄膜是研究最多的产生纯自旋电流的材料之一。我们将构建一个基于YIG/Au/Py（坡莫合金）结构的器件，其中Py用作自旋电流探测器。高效、定量的自旋电流探测器的发展是自旋电子学技术的重要组成部分。我们将与E教授合作。Girt的小组在开发具有高垂直磁各向异性（PMA）的磁性超晶格方面的工作，该超晶格用于高密度磁存储介质和MRAM。在SFU的4D实验室的新的洁净室设施，我们可以制造纳米尺寸的柱结构，可以通过自旋极化电流或SHE和SOT驱动。* 我们独特的实验研究使我们能够开展广泛的计划，推进基于自旋泵，自旋电流传输和自旋扭矩机制的材料和系统开发的工程和基础科学进展。

Summary***The spin of the electron rather than its charge has created remarkable opportunities in electronics, coined spintronics. The rapid progress in this field requires further advances in understanding of spin interactions in nanoscopic geometries. Our studies involve spin dynamics with emphasis on the study of pure spin currents unaccompanied by a net electric charge. ****a) We are going to continue to study the spin current transport in non-magnetic metallic layers which serve in spintronics, as interconnects between the magnetic source and sink terminals. Particular emphases will be put on heavy metallic thin films which have a large spin orbit interaction, electron spin correlations, and high resistivity with the spatial electron localization. Heavy metal Pt, Ta, and W metallic films are very attractive in spintronics. They have very large Spin Hall Effect (SHE) and interface Spin Orbit Torque (SOT), allowing one to operate Magnetic Random Access Memory (MRAM) by using an electric current in heavy metals. After firmly establishing the spin transport parameters in Pt, Ta, and W, we will study the reflection of spin current at the Au/(Pt,Ta,W) interfaces. We expect, based on our PRL 2013, to observe quantum well states in Fe/Au/Pd,Pt,Ta,W heterostructures due to spatial confinement of spin current in the Au layer. This is fundamental physics because quantum well states are typical to reversible processes while spin pumping is an irreversible process. Heavy metals will be used also in spin torque driven nanopillar devices with the intention to further understand the role of interface SOT and spin loss memory, allowing one to improve Magnetic Random Access Memory (MRAM) architecture. ****b)Large spin currents can be achieved by using a large angle of precession of the magnetic moment at the ferromagnet/normal metal interface. In fact, this can lead to a comparable spin current using a spin polarized net charge current in spin torque devices. Yttrium Iron Garnet (YIG) films have become one of the most studied materials for generating pure spin currents. We are going to construct a device that is based on YIG/Au/Py(Permaloy) structure, where Py is used as a spin current detector. The development of efficient and quantitative spin current detectors is an important part of spintronic technology.****c)We will collaborate with Prof. E. Girt's group in the development of magnetic superlattices with high perpendicular magnetic anisotropy (PMA) for applications directed to high density magnetic memory media and MRAM. With the new clean room facility in SFU's 4D LABS, we can fabricate nanosize pillar structures which can be driven either by spin polarized current or SHE and SOT. ***Our unique experimental research enables us to carry out a broad program advancing both the engineering and basic science progress in the development of materials and systems based on spin pumping, spin current transport and spin torque mechanism.***********