Theory and Modelling for Antiferromagnetric Materials-based Spintronic Devices

基于反铁磁材料的自旋电子器件的理论和建模

• 批准号: 1708180
• 负责人: Shufeng Zhang
• 金额: $ 30万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708180&HistoricalAwards=false
• 关键词: Theory; Modelling; Antiferromagnetric; Materials; based

Spin-based electronic devices for information storage and memory rely on the efficient control of the spin up and spin down states. Conventionally, the direction of magnetization of a small magnet dictates these spin states and thus ferromagnetic materials are essential for spintronic devices. However, there are a few obstacles for further advancing the spin devices based on the ferromagnetic materials: the electric current density for switching the magnetization direction remains too large and the size reduction of memory elements is fundamentally difficult due to a strong magnetic interaction among nanometer-sized magnetic elements in close vicinity. The present proposal is to explore alternative magnetic materials known as antiferromagnets for spin-based devices. Antiferromagnetic materials are made of two or more sub-lattices in which the spins of each sub-lattice are oriented in one direction, but the total or net magnetization is zero. In spite of many intriguing and superior electric and magnetic properties, the antiferromagnetic materials have not been used as magnetically active elements for spin device applications. If one is able to manipulate spin states in antiferromagnetic materials, one would create a disruption spin-based technology which is faster, denser, and more energy efficient, compared to ferromagnetic based devices. The proposal calls for a comprehensive theoretical investigation on how devices made of the antiferromagnetic materials and their multilayers respond to the time-dependent external electric and magnetic fields. The goal is to evaluate the feasibility of antiferromagnetic based spin devices and to find optimal materials parameters in various structure. The educational components of the proposal include strong graduate student participations in research, training, and visiting industrial research laboratories, as well as for PI to develop a spintronics course related to this research project.In today's spintronics, spins of conduction electrons play a pivotal role in carrying angular momentum information and manipulating the magnetization dynamics of magnetic nanostructures. Antiferromagnetic materials have no net spin or magnetization, but they have two distinct magnetic characteristics: a staggered magnetic moment and a quasi-particle excitation known as antiferromagnetic magnons. Both staggered moment and magnons could carry angular momentum and serve as spin information propagators. This proposal aims at a comprehensive study on the roles of these carriers. In metallic systems, a theory of coupled electron-magnon conduction, which is capable of predicting new magnetotransport properties, will be developed. In insulating materials, the mutual dependence of the direction of staggered moments and the non-equilibrium number of magnons is the main focus of research. The proposal further explores the following novel spin-dependent properties of antiferromagnetic-based multilayered structures: 1) Quantitatively determining spin current from the flow of the electron spins, the staggered magnetic moments, and magnons, as well as their conversion rates across interfaces in various multilayered systems. 2) Investigating the interplay between the staggered moments and magnons for magnetic control. 3) Exploring possible spintronics device concepts based on the antiferromagnetic materials. If successful, the present research could reveal knowledge for staggered magnetic momentum and magnons which may have superior capabilities for enhanced spin information propagation in spintronic applications.

用于信息存储和存储器的基于自旋的电子器件依赖于对上自旋和下自旋状态的有效控制。通常，小磁体的磁化方向决定这些自旋状态，因此铁磁材料对于自旋电子器件是必不可少的。然而，进一步推进基于铁磁材料的自旋器件存在一些障碍：用于切换磁化方向的电流密度仍然太大，并且由于附近纳米尺寸的磁性元件之间的强磁相互作用，存储元件的尺寸减小从根本上是困难的。目前的建议是探索替代磁性材料称为反铁磁体的自旋为基础的设备。反铁磁材料是由两个或多个子晶格组成，其中每个子晶格的自旋都沿一个方向取向，但总磁化或净磁化为零。尽管反铁磁材料具有许多令人感兴趣的和上级的电和磁性能，但其还没有被用作自旋器件应用的磁激活元件。如果人们能够操纵反铁磁材料中的自旋状态，那么与基于铁磁的设备相比，人们将创造一种更快、更密集、更节能的基于自旋的破坏技术。该提案要求对由反铁磁材料及其多层膜制成的器件如何响应随时间变化的外部电场和磁场进行全面的理论研究。目的是评估基于反铁磁自旋器件的可行性，并在各种结构中找到最佳的材料参数。该计划的教育部分包括研究生参与研究、培训和参观工业研究实验室，以及PI开发与该研究项目相关的自旋电子学课程。在当今的自旋电子学中，传导电子的自旋在携带角动量信息和操纵磁性纳米结构的磁化动力学方面发挥着关键作用。反铁磁材料没有净自旋或磁化，但它们有两个不同的磁性特征：交错磁矩和称为反铁磁磁磁振子的准粒子激发。交错矩和磁振子都可以携带角动量，作为自旋信息的传播子。本提案旨在全面研究这些承运人的作用。在金属系统中，将发展能够预测新的磁输运性质的电子-磁振子耦合传导理论。在绝缘材料中，磁振子的错列矩方向和非平衡态数的相互依赖性是研究的主要焦点。该提议进一步探索了以下基于反铁磁的多层结构的新颖的自旋相关性质：1）从电子自旋、交错磁矩和磁振子的流动以及它们在各种多层系统中跨界面的转换率定量确定自旋电流。2)研究交错矩与磁振子间的相互作用以控制磁场。3)探索基于反铁磁材料的自旋电子学器件概念。如果成功的话，目前的研究可以揭示交错磁动量和磁振子的知识，这可能具有上级能力，增强自旋信息传播的自旋电子学应用。

项目成果

Interplay of magnon and electron currents in magnetic heterostructure

磁性异质结构中磁振子和电子流的相互作用

• DOI: 10.1103/physrevb.96.024449
• 发表时间: 2017
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Cheng, Yihong;Chen, Kai;Zhang, Shufeng
• 通讯作者: Zhang, Shufeng

Spin transport and dynamic properties of two-dimensional spin-momentum locked states

二维自旋动量锁定态的自旋输运和动态特性

• DOI: 10.1209/0295-5075/130/58001
• 发表时间: 2020
• 期刊: EPL (Europhysics Letters
• 作者: Tang, Ping;Han, Xiufeng;Zhang, Shufeng
• 通讯作者: Zhang, Shufeng

Giant magneto-spin-Seebeck effect and magnon transfer torques in insulating spin valves

• DOI: 10.1063/1.5018411
• 发表时间: 2018-01-29
• 期刊: APPLIED PHYSICS LETTERS
• 影响因子: 4
• 作者: Cheng, Yihong;Chen, Kai;Zhang, Shufeng
• 通讯作者: Zhang, Shufeng

Amplification of spin-transfer torque in magnetic tunnel junctions with an antiferromagnetic barrier

• DOI: 10.1103/physrevb.99.104417
• 发表时间: 2019-03-13
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Cheng, Yihong;Wang, Weigang;Zhang, Shufeng
• 通讯作者: Zhang, Shufeng