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Dilute Magnetic 2D-Semiconductors: Fundamentals for Device Applications

稀磁二维半导体：设备应用基础知识

基本信息

批准号：
2118414
负责人：
Matthias Batzill
金额：
$ 45.7万
依托单位：
University of South Florida
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-01 至 2025-07-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2118414&HistoricalAwards=false
关键词：
Dilute Magnetic 2D Semiconductors Fundamentals

项目摘要

Non-technical DescriptionMagnetic semiconductors are materials with magnetic properties that are also semiconductors. They can be utilized in applications such as non-volatile memories and enable spin-based electronics with applications such as quantum computing. However, most semiconductors are non-magnetic. There has been some success in making magnetic semiconductors through doping conventional semiconductors with magnetic impurities. Usually only low magnetic transition temperatures have been achieved, limiting potential applications. This project will investigate two-dimensional (2D) magnetic semiconductors that have the potential to reach room temperature magnetism. 2D materials are extended in a plane but are only a few atoms thick. Such planar materials have potential for future devices because two-dimensional crystals can be stacked with atomically sharp interfaces. 2D materials are also sensitive to their environment and thus their properties can be tuned through interfaces or external stimuli. In this research the fundamental properties of magnetic dopants in 2D materials will be investigated in order to gain insight on the mechanisms that allow introduction and tuning of magnetism in these materials. The ultimate goal is to develop reliable approaches to realize 2D magnetic semiconductors that function above room temperature. The research has the potential to lead to the development of tunable spintronic devices based on new multifunctional materials. Importantly, this project provides training for graduate students in contemporary materials science with technological relevance and will broaden their experience through international collaborations and research activities.Technical DescriptionThis project explores magnetic dopants in the 2D-semiconductors MoS2 and WSe2. Doped films and monolayers will be grown by low temperature-molecular beam epitaxy to enable the efficient incorporation of various transition metal dopants. The successful doping and the atomic scale dopant-structures will be investigated by scanning tunneling microscopy and spectroscopy to gain insight on the dopant induced defect states that control the local magnetic moments. The role of dopant-element, structure, and concentration on the magnetic properties is investigated by systematically varying materials processing conditions and investigation of the magnetic properties by magnetometry and synchrotron x-ray magnetic circular dichroism studies. The experimental observations are correlated to theoretical density functional calculations. Tunability of the magnetic properties by charge transfer doping in ultrathin films is also studied. This study will give insight on the magnetic coupling mechanism of the dopants and the role of secondary defects in tuning of the magnetism. The study exploits the 2D nature of the material systems for both gaining better insight in the general mechanism for diluted magnetic semiconductors, as well as for the potential of exploiting their atomically sharp interfaces in van der Waals heterostructures for combining magnetic materials with materials with diverse quantum properties as well as for magnetic device structures. Fundamentally, this activity aims at determining the magnetic coupling between magnetic dopants to find the reason for the apparently higher Curie temperatures in 2D magnetic diluted semiconductors compared to traditional semiconductors.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.

非技术描述磁性半导体是具有磁性的材料，也是半导体。它们可以用于非易失性存储器等应用，并使基于自旋的电子器件具有量子计算等应用。然而，大多数半导体是非磁性的。通过在传统半导体中掺杂磁性杂质来制造磁性半导体已经取得了一些成功。通常只有低的磁转变温度已经实现，限制了潜在的应用。该项目将研究有可能达到室温磁性的二维（2D）磁性半导体。二维材料在平面上延伸，但只有几个原子厚。这种平面材料具有未来器件的潜力，因为二维晶体可以堆叠原子级尖锐的界面。2D材料对环境也很敏感，因此它们的特性可以通过界面或外部刺激进行调整。在这项研究中，将研究2D材料中磁性掺杂剂的基本性质，以深入了解允许在这些材料中引入和调节磁性的机制。最终目标是开发可靠的方法来实现在室温以上工作的2D磁性半导体。该研究有可能导致基于新的多功能材料的可调谐自旋电子器件的发展。重要的是，该项目为研究生提供当代材料科学与技术相关性的培训，并将通过国际合作和研究活动拓宽他们的经验。技术说明该项目探讨二维半导体MoS 2和WSe 2中的磁性掺杂剂。掺杂薄膜和单层将通过低温分子束外延生长，以使各种过渡金属掺杂剂的有效结合。成功的掺杂和原子尺度的掺杂剂结构将通过扫描隧道显微镜和光谱学进行研究，以深入了解控制局部磁矩的掺杂剂诱导的缺陷态。掺杂元素，结构和浓度对磁性能的作用进行了研究，通过系统地改变材料的加工条件和调查的磁性能的磁力和同步加速器X-射线磁性圆二色性研究。实验观察相关的理论密度泛函计算。还研究了电荷转移掺杂对磁性能的可调谐性。这项研究将提供洞察的磁性耦合机制的掺杂剂和二次缺陷的磁性调谐中的作用。该研究利用了材料系统的2D性质，以便更好地了解稀磁半导体的一般机制，以及利用它们在货车德瓦尔斯异质结构中的原子尖锐界面的潜力，将磁性材料与具有不同量子特性的材料结合起来，以及用于磁性器件结构。基本上，该活动旨在确定磁性掺杂剂之间的磁耦合，以找出2D磁稀释半导体的居里温度明显高于传统半导体的原因。该奖项反映了NSF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。