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特性的材料，也是半导体。它们可以用于非挥发性记忆等应用中，并通过量子计算等应用实现基于自旋的电子设备。但是，大多数半导体都是非磁性的。通过掺杂具有磁性杂质的常规半导体使磁性半导体取得了一些成功。通常，只有低磁过渡温度才能限制潜在的应用。该项目将研究有可能达到室温磁性的二维（2D）磁性半导体。 2D材料在平面中延伸，但只有几个原子厚。这种平面材料具有未来设备的潜力，因为二维晶体可以用原子尖锐的界面堆叠。 2D材料也对其环境敏感，因此可以通过界面或外部刺激来调整其性能。在这项研究中，将研究2D材料中磁性掺杂剂的基本特性，以了解允许在这些材料中引入和调整磁性的机制。最终目标是开发可靠的方法，以实现高于室温的2D磁性半导体。这项研究有可能导致基于新的多功能材料开发可调的自旋设备。重要的是，该项目为当代材料科学领域的研究生提供了技术相关性的培训，并将通过国际合作和研究活动来扩大他们的经验。技术描述该项目探索了2D-Sementemonductors MOS2和WSE2中的磁性掺杂剂。掺杂的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有效掺入。将通过扫描隧道显微镜和光谱法来研究成功的掺杂和原子量表掺杂剂结构，以了解控制局部磁矩的掺杂剂诱导的缺陷状态。通过系统地变化的材料加工条件以及通过磁力仪和同步X射线X射线磁循环二色性研究来研究掺杂元素，结构和浓度对磁性特性的作用。实验观察结果与理论密度的功能计算相关。还研究了通过电荷转移掺杂在超薄膜中的可调性。这项研究将深入了解掺杂剂的磁耦合机制以及次级缺陷在磁性调谐中的作用。该研究利用了材料系统的2D性质，以更好地了解稀释的磁性半导体的一般机制，以及利用其在范德华异质结构中利用其原子尖锐的界面，以将磁性材料与材料与多样的量子特性以及磁性设备结构相结合。从根本上讲，这项活动旨在确定磁性掺杂剂之间的磁耦合，以找到与传统半导体相比，在2D磁性稀释的半导体中显然居里温度更高的原因。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和广泛的影响来评估NSF的法定任务，并被认为是值得的支持。