Experimental investigation of topological excitations in magnetic tunneling junctions

磁隧道结拓扑激发的实验研究

• 批准号: 1809155
• 负责人: Hong-Wen Jiang
• 金额: $ 51万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1809155&HistoricalAwards=false
• 关键词: Experimental; investigation; topological; excitations; magnetic

Nontechnical Abstract: In recent years, it has been discovered that properties hidden inside certain materials can be excited electrically or magnetically, to design the next generation of electronics. Skyrmion, a nanoscale whirling magnetic pattern, is an example of such topological excitations in magnetic materials. The magnetic tunnel junction is arguably the most promising spintronics device, developed in the recent years, for data storage, sensing, and logic computation. Generally, in such applications two opposite ferromagnetic states are used to store binary data in the magnetic tunneling junctions. This experimental research develops new ways to create, probe, and manipulate the magnetic skyrmion states in the magnetic tunnel junctions. The skyrmion-based magnetic tunnel junctions are expected to consume less energy, operate at a higher speed, and be more robust against material disorder, providing a platform for significant technological advances. The project prepares graduate students for skilled research in both spintronics and microwave electronics, technical areas that are of great economic importance to our society, and well-trained physicists in these areas are in high demand. The development of a graduate level course on nano-magnetics and spintronics effectively integrates the proposed research into a teaching topic in demand, to fulfill the needs of students from multidisciplinary areas such as Physics, Electrical Engineering, Material Sciences, and Chemistry.Technical Abstract: The objective of this research is to study individual and interacting magnetic skyrmions in magnetic tunnel junctions. Current-driven spin-transfer torque, voltage controlled magnetic anisotropy, and applied magnetic field vector are used as a means to control the interplay between the Heisenberg exchange interaction, responsible for ferromagnetism, and the Dzyaloshinskii-Moriya interaction, which gives rise to stable skyrmions. A phase diagram for competing magnetic excitations is mapped out experimentally. Sub-nanosecond electrical voltage pulses are used to deterministically create and annihilate individual skyrmions. A resonant spectroscopy technique is developed to use the breathing mode of skyrmions to carry out characterizations, including energy dispersion, core size, etc. Interacting skyrmions in larger devices, as in the case of a skyrmion crystal, are studied. The implications of disorder, particularly for edge imperfection, are investigated.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要：近年来，人们发现隐藏在某些材料内部的特性可以通过电或磁的方式激发，以设计下一代电子产品。斯格明子（Skyrmion）是一种纳米级旋转磁性图案，是磁性材料中此类拓扑激发的一个例子。 磁隧道结可以说是近年来开发的最有前途的自旋电子器件，用于数据存储、传感和逻辑计算。 通常，在此类应用中，两个相反的铁磁状态用于在磁隧道结中存储二进制数据。这项实验研究开发了创建、探测和操纵磁隧道结中磁斯格明子态的新方法。 基于斯格明子的磁隧道结预计将消耗更少的能量，以更高的速度运行，并且对材料无序的抵抗力更强，从而为重大技术进步提供平台。该项目为研究生进行自旋电子学和微波电子学的熟练研究做好准备，这些技术领域对我们的社会具有重要的经济重要性，并且这些领域对训练有素的物理学家的需求量很大。纳米磁学和自旋电子学研究生课程的开发有效地将拟议的研究融入到所需的教学主题中，以满足物理、电气工程、材料科学和化学等多学科领域学生的需求。技术摘要：这项研究的目的是研究磁隧道结中单个和相互作用的磁斯格明子。电流驱动的自旋转移矩、电压控制的磁各向异性和施加的磁场矢量被用作控制海森堡交换相互作用（负责铁磁性）和 Dzyaloshinskii-Moriya 相互作用（产生稳定的斯格明子）之间相互作用的手段。 通过实验绘制了竞争磁激励的相图。亚纳秒电压脉冲用于确定性地产生和消灭单个斯格明子。 开发了一种共振光谱技术，利用斯格明子的呼吸模式来进行表征，包括能量色散、核心尺寸等。研究了较大装置中的相互作用的斯格明子，例如斯格明子晶体。 对无序的影响，特别是边缘缺陷的影响进行了调查。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Experimental Observation of Single Skyrmion Signatures in a Magnetic Tunnel Junction

磁隧道结中单个斯格明子特征的实验观察

• DOI: 10.1103/physrevlett.122.257201
• 发表时间: 2019-06
• 期刊: Physical Review Letters
• 影响因子: 8.6
• 作者: Penthorn, N. E.;Hao, X.;Wang, Z.;Huai, Y.;Jiang, H. W.
• 通讯作者: Jiang, H. W.