CAREER: Magnetism and Spintronics in Quasi-two-dimensional Magnetic Hybrid Metal Halides: From Bulk to 2D limit

电子电荷在计算机中的流动使计算机能够有效地进行数据处理、存储和信息传输。除了电荷，电子还具有自旋的量子特性。它们要么处于“自旋向上”的状态，要么处于“自旋向下”的状态，要么处于两种状态的混合。自旋电子学是量子信息科学的推动者，在量子信息科学中，信息是由自旋而不是电荷携带的。通过操纵自旋，计算机可以用比目前可能的更少的功率和更低的成本处理信息。磁性材料的超薄薄膜，低至原子薄层，将成为探索基本自旋现象的理想平台，并具有巨大的潜力，可以为更快、更节能的量子计算机创造新的设计。本研究旨在探索一类由交变磁性和非磁性原子层组成的新型“杂化”磁性材料的自旋行为。相邻磁层之间的相互作用很弱，因此它们彼此有效地隔离，由此可以追求超薄材料中的自旋控制。这类材料可以作为在原子水平上研究自旋态的跳板，从而使下一代高性能微处理器成为可能。该项目还将对高中生和本科生进行物理、材料科学和化学的教育，并为高科技行业提供劳动力培训。学生将通过高级实验课程体验研究中使用的关键技术，同时鼓励学生的独立性和创造力。这种更广阔的视野将有助于吸引年轻人从事未来的STEM职业。技术描述二维磁性材料通过在二维极限下操纵磁化强度来直接控制自旋信息。这项研究的重点是开发一类新的准二维磁性杂化金属卤化物（HMHs），它具有低维磁性和定制的层内/层间交换耦合，受益于化学的多功能性。经典的二维磁性能将通过一套磁力计、磁光学和磁电阻技术，从块状晶体到几层超薄膜进行演示。通过取代有机阳离子、金属和卤素元素，可以实现对静态低维磁序和交换耦合的控制。采用变温铁磁共振和自旋泵浦测量，研究了二维磁性高磁hs在不同磁相下相干产生的磁振子，以及可调谐动态耦合诱导的丰富的共振模式结构。这项研究将二维磁性从无机二维范德华晶体扩展到广泛的未知二维杂化金属卤化物，为设计新的二维磁体推出了新的策略。通过“高级高级实验”课程，为本科生设计具体的高级实验项目，传播铁磁共振和自旋泵浦的基本概念。激光干涉仪和磁光学将通过各种推广平台和高级实验课程进行传播，将科学成果融入高中和本科生的教育中。这些计划为学生提供了一个相对开放的科学项目的实践，从早期的构建/调试阶段，通过仔细的数据分析，到可以清楚地与其他科学家交流的程度。熟悉这一过程的严谨性是训练他们成为未来科学家的最重要部分。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical DescriptionThe flow of an electronic charge through computers enables their efficient data processing, storage, and transfer of information. In addition to charge, electrons also possess the quantum property of spin. They can be found either in the ‘spin-up’ state, the ‘spin-down’ state, or the mixture of both states. Spin-based electronics - spintronics - is an enabler of quantum information science, where information is carried by spin, rather than charge. By manipulating spin, information can be processed by computers using much less power and at lower cost than is currently possible. Ultrathin films, down to an atomically thin layer, of magnetic materials will be an ideal platform for exploring fundamental spin phenomena and have great potential to create novel designs for faster and more energy efficient quantum computers. This research aims to explore the spin behavior in a new class of ‘hybrid’ magnetic materials which consist of alternating magnetic and nonmagnetic atomic layers. The interaction between the neighboring magnetic layers is weak so that they are effectively isolated from one another, from which the control of spin in ultra-thin materials can be pursued. This class of materials can be a launching pad into studying the spin states on the atomic level to enable the next generation of high-performance microprocessors. This project will also educate both high school and undergraduate students in Physics, Materials Science, and Chemistry, and provide workforce training for high technology industries. Students will experience key techniques that are used in the research through advanced lab courses that also encourage students’ independence and creativity. This wider perspective will help to attract young people to future STEM careers.Technical Description2D magnetic materials empower the direct control of spin information by manipulating magnetization at the 2D limit. This research focuses on developing a new class of quasi-2D magnetic hybrid metal halides (HMHs) that possess both low-dimensional magnetism and tailored intra-/inter-layer exchange couplings benefiting from chemical versatility. Classical 2D magnetic properties will be demonstrated from bulk crystals down to few-layered ultrathin films using a suite of magnetometers, magneto-optics, and magnetoresistance techniques. By substituting organic cations, metal, and halogen elements, control over static low-dimensional magnetic order and exchange couplings can be achieved. Variable-temperature ferromagnetic resonance and spin pumping measurements are applied to study coherently generated magnons at different magnetic phases of 2D magnetic HMHs as well as a rich structure of resonance modes induced by tunable dynamic couplings. This research extends 2D magnetism from inorganic 2D van der Waals crystals to a wide spectrum of uncharted 2D hybrid metal halides, launching a new strategy for the design of new 2D magnets. Specific senior lab projects for undergraduate students will be designed through an ‘Advanced Senior Lab’ course to disseminate the basic concepts of ferromagnetic resonance and spin pumping. A laser interferometer and magneto-optics will be disseminated through various outreach platforms and the advanced senior lab course, to integrate scientific achievements into the high school and undergraduate students’ educations. These plans provide practice for students taking a relatively open-ended science project from its early construction/debugging stages, through careful data analysis, to the point where it can be communicated clearly to other scientists. Familiarity with the rigors of this process is the most important part of their training as future scientists.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.