Spin dynamics in magnetic nanostructures

磁性纳米结构中的自旋动力学

• 批准号: RGPIN-2016-04329
• 负责人: Heinrich, Bretislav
• 金额: $ 3.95万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=653370
• 关键词: Spin; dynamics; magnetic; nanostructures

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.***********

摘要***电子的自旋而不是其电荷在电子学领域创造了非凡的机会，即自旋电子学。该领域的快速进展需要进一步加深对纳米几何形状中自旋相互作用的理解。我们的研究涉及自旋动力学，重点是研究不伴随净电荷的纯自旋电流。 ****a）我们将继续研究非磁性金属层中的自旋电流传输，这些金属层在自旋电子学中用作磁源和汇端子之间的互连。将特别关注具有大自旋轨道相互作用、电子自旋相关性以及具有空间电子局域化的高电阻率的重金属薄膜。重金属Pt、Ta和W金属薄膜在自旋电子学中非常有吸引力。它们具有非常大的自旋霍尔效应（SHE）和接口自旋轨道扭矩（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）。在确定了 Pt、Ta 和 W 中的自旋输运参数后，我们将研究 Au/(Pt,Ta,W) 界面上自旋电流的反射。根据我们的 PRL 2013，我们期望观察到由于 Au 层中自旋电流的空间限制而导致的 Fe/Au/Pd、Pt、Ta、W 异质结构中的量子阱态。 这是基础物理学，因为量子阱态是可逆过程的典型特征，而自旋泵浦是不可逆过程。 重金属还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，从而改进磁随机存取存储器 (MRAM) 架构。 ****b）通过在铁磁体/普通金属界面处使用大角度的磁矩进动可以实现大自旋电流。事实上，这可以在自旋扭矩器件中使用自旋极化净电荷电流产生可比较的自旋电流。钇铁石榴石 (YIG) 薄膜已成为研究最多的用于产生纯自旋电流的材料之一。我们将构建一个基于 YIG/Au/Py(Permaloy) 结构的器件，其中 Py 用作自旋电流探测器。开发高效、定量的自旋电流探测器是自旋电子技术的重要组成部分。****c)我们将与E. Girt教授的团队合作开发具有高垂直磁各向异性（PMA）的磁性超晶格，用于高密度磁存储介质和MRAM的应用。借助 SFU 4D 实验室中的新洁净室设施，我们可以制造纳米尺寸的柱结构，该结构可以由自旋极化电流或 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，在基于自旋泵浦、自旋流输运和自旋扭矩机制的材料和系统的开发中推进工程和基础科学的进步。************