EAGER: Magnetic Nanostructures with Perpendicular Anisotropy

EAGER：具有垂直各向异性的磁性纳米结构

• 批准号: 1543582
• 负责人: Kai Liu
• 金额: $ 4.5万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1543582&HistoricalAwards=false
• 关键词: EAGER; Magnetic; Nanostructures; Perpendicular; Anisotropy

Non-Technical AbstractA key attribute of a magnetic material is the ability to retain its magnetic moment in certain directions, or magnetic anisotropy. For example, an iron needle is usually magnetized along its long axis and a thin iron foil would have its moments lying in the film plane. Certain nanoscale magnets in thin film forms, however, prefer to orient their moments perpendicular to the films - known as perpendicular magnetic anisotropy. Such nanomagnets are technologically important, as they allow much more efficient information storage at higher densities, analogous to the benefits of building skyscrapers with small real-estate footprints. This project investigates two types of such nanomaterials that have potentially transformative technological impacts: 1. ordered alloys of iron/platinum-based materials as storage media in next generation ultrahigh density magnetic recording; 2. a novel type of nanomagnet arrays where the magnetic moments take up a special arrangement known as the skyrmion state. The magnetic skyrmions offer potentially new mechanisms for information storage that is not only robust, but also highly energy efficient, expected to be at a tiny fraction of the energy cost of current technologies. Students involved will receive exposure to research experiences in university, national laboratory and user-facility, and industrial research and development. Technical AbstractAlloys of FePt-based materials in the ordered phase are promising media choices for the emerging heat-assisted magnetic recording technology due to their high anisotropy, large saturation magnetization, and moderate Curie temperature. This project addresses critical challenges in the convenient realization of the high anisotropy phase, and understanding and control over the switching field distribution. Thin films of FePt-based alloys in the ordered phase are investigated. Basic understanding and control of the magnetization reversal are gained through magnetometry and first-order reversal curve studies at elevated temperatures. The second research area focuses on magnetic skyrmions that exhibit topologically protected quantum states and other unique topological phenomena. Hybrid skyrmion lattices based on perpendicular anisotropy films are synthesized and investigated to demonstrate the ground state at room temperature. A set of magnetic field sequences is followed to establish the skyrmion lattices, as well as vortex lattices and mixed lattices for comparison. Magnetic imaging, polarized neutron reflectometry, magneto-transport studies, and micromagnetic simulations are carried out to probe the skyrmions and their responses to external stimuli. These artificial skyrmions are expected to be stable over wide temperature and field ranges, thus offering an exciting platform to explore the intriguing physics in such exotic spin textures.

非技术摘要磁性材料的一个关键属性是在某些方向上保留其磁矩的能力，或磁各向异性。例如，铁针通常沿其长轴磁化，薄铁箔的磁矩位于薄膜平面上。然而，某些薄膜形式的纳米级磁体更喜欢将其磁矩定向为垂直于薄膜——称为垂直磁各向异性。这种纳米磁体在技术上非常重要，因为它们可以以更高的密度更有效地存储信息，类似于用较小的房地产占地面积建造摩天大楼的好处。 该项目研究了两种具有潜在变革性技术影响的纳米材料： 1. 铁/铂基材料的有序合金，作为下一代超高密度磁记录的存储介质； 2.一种新型纳米磁体阵列，其中磁矩呈现一种称为斯格明子态的特殊排列。磁性斯格明子为信息存储提供了潜在的新机制，该机制不仅强大，而且能源效率高，预计其能源成本只是当前技术的一小部分。参与的学生将获得大学、国家实验室和用户设施以及工业研究和开发的研究经验。技术摘要有序相 FePt 基材料合金由于其高各向异性、大饱和磁化强度和适中的居里温度，是新兴热辅助磁记录技术的有前途的介质选择。该项目解决了方便实现高各向异性相位以及理解和控制切换场分布方面的关键挑战。研究了有序相中 FePt 基合金的薄膜。通过高温下的磁力测量和一阶反转曲线研究获得了对磁化反转的基本了解和控制。第二个研究领域侧重于表现出拓扑保护量子态和其他独特拓扑现象的磁性斯格明子。合成并研究了基于垂直各向异性薄膜的混合斯格明子晶格，以证明室温下的基态。遵循一组磁场序列来建立斯格明子晶格，以及涡旋晶格和混合晶格以进行比较。进行磁成像、偏振中子反射测量、磁输运研究和微磁模拟来探测斯格明子及其对外部刺激的响应。这些人造斯格明子预计将在较宽的温度和场范围内保持稳定，从而提供一个令人兴奋的平台来探索这种奇异自旋纹理中有趣的物理现象。

项目成果

Magnetic fingerprint of interfacial coupling between CoFe and nanoscale ferroelectric domain walls

CoFe与纳米级铁电畴壁之间界面耦合的磁指纹

• DOI: 10.1063/1.4961545
• 发表时间: 2016-08
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Zhang, Qintong;Murray, Peyton;You, Lu;Wan, Caihua;Zhang, Xuan;Li, Wenjing;Khan, Usman;Wang, Junling;Liu, Kai;Han, Xiufeng
• 通讯作者: Han, Xiufeng

Controllable positive exchange bias via redox-driven oxygen migration

通过氧化还原驱动的氧迁移实现可控的正交换偏压

• DOI: 10.1038/ncomms11050
• 发表时间: 2016-03
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: Gilbert, Dustin A.;Olamit, Justin;Dumas, Randy K.;Kirby, B. J.;Grutter, Alexander J.;Maranville, Brian B.;Arenholz, Elke;Borchers, Julie A.;Liu, Kai
• 通讯作者: Liu, Kai

Synthesis, Characterization, and Low Temperature Transport Properties of Eu 11–x Yb x Cd 6 Sb 12 Solid-Solution Zintl Phases

Eu 11-x Yb x Cd 6 Sb 12 固溶体 Zintl 相的合成、表征及低温输运性能

• DOI: 10.1021/acs.inorgchem.6b01947
• 发表时间: 2016-11
• 期刊: Inorganic Chemistry
• 影响因子: 4.6
• 作者: Kazem, Nasrin;Cooley, Joya;Burks, Edward C.;Liu, Kai;Kauzlarich, Susan M.
• 通讯作者: Kauzlarich, Susan M.

In-plane/out-of-plane disorder influence on the magnetic anisotropy of Fe 1− y Mn y Pt-L1 0 bulk alloy

面内/面外无序对Fe 1−y Mn y Pt-L1 0 大块合金磁各向异性的影响

• DOI: 10.1063/1.4944534
• 发表时间: 2016-03
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Cuadrado, R.;Liu, Kai;Klemmer, Timothy J.;Chantrell, R. W.
• 通讯作者: Chantrell, R. W.

Magnetization Reversal of Nickel Three-Dimensional Anti-sphere Arrays

镍三维反球体阵列的磁化反转

• DOI: 10.1109/lmag.2016.2616325
• 发表时间: 2016-10
• 期刊: IEEE Magnetics Letters
• 影响因子: 1.2
• 作者: Yu, Le;Yan, Z.Y.;Yang, H.C.;Chai, X.Z.;Li, B.Q.;Moeendarbari, Sina;Hao, Y.W.;Zhang, Di;Feng, Gang;Han, Ping;et al
• 通讯作者: et al