Synthesis and Properties of Heterostructures Containing Magnetic 2d Layers Not Found As Bulk Compounds

含有未发现为本体化合物的磁性二维层的异质结构的合成和性能

• 批准号: 2219512
• 负责人: David Johnson
• 金额: $ 45万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219512&HistoricalAwards=false
• 关键词: Synthesis; Properties; Heterostructures; Containing; Magnetic

NON-TECHNICAL SUMMARYThe 2010 Nobel prize in physics was awarded for the discovery of novel properties in monolayers of compounds with two dimensional (2D) structures that are not present in the bulk compounds. The resulting field of science - 2D materials and stacked layers of 2D materials known as heterostructures - has exponentially expanded as theorists proposed new exotic properties and experimentalists discovered new properties in monolayers and heterostructures. Currently the preparation of heterostructures is done by cleaving bulk materials to the monolayer limit and stacking them in designed sequences. This approach is limited to constituents that are stable as bulk compounds which are cleavable. New synthesis approaches are needed that enable preparation of heterostructures at a wafer scale, that provide a wider selection of constituent layers, and that provide control over the nanoarchitecture (stacking sequence and thickness of constituent layers). In this project, with the support of the Solid State and Materials Chemistry and Ceramics Programs in the Division of Materials Research, Dr. David Johnson and his research group at the University of Oregon, will develop new synthetic approaches to preparing heterostructures containing 2D magnetic constituent layers with structures and compositions that are not thermodynamically stable as isolated compounds. Three different strategies, all of which use precursors with targeted composition profiles that match that of the targeted heterostructures, are being tested. This research program provides a broad technical background for graduate students in deposition technologies, thin film characterization techniques, and physical phenomena that occur in 2D heterostructures. This training enables them to thrive in a variety of future careers (high tech industries, academia, or national laboratories). Internships will provide an opportunity for graduate students to “test drive” future careers while expanding their knowledge base, leading to more productive researchers. Engaging undergraduate students in this research enables them to apply principles learned in classes to solve research challenges. Providing undergraduate research opportunities is a critical tool to increase the number and diversity of students pursuing science as a career. TECHNICAL SUMMARYWith the support of the Solid State and Materials Chemistry and Ceramics Programs in the Division of Materials Research, Dr. David Johnson and his research group at the University of Oregon will develop synthetic approaches to preparing heterostructures containing 2D magnetic constituent layers with structures and compositions that are not thermodynamically stable as isolated compounds. Synthetic targets include diselenides (TSe2) and rock salt structured Pb2+nT1+mSe3+n+m layers, where T = Cr, Mn, Fe and Ni. Three synthesis strategies, which use precursors with targeted local composition and nanoarchitecture to control nucleation and growth, are being tested. One strategy is to prepare a precursor designed such that one layer crystalizes as 2D sheets separated by amorphous layers of controlled composition. The resulting 2D form factor and composition of the interleaved amorphous layers as well as the structure of adjacent crystalline layers will be used to control the nucleation and growth of the metastable constituent layers. A second strategy will be to seed nucleation of the desired structures by controlling local composition. A third strategy will be to use charge transfer from an adjacent layer to stabilize the targeted structures. The companion constituents in the targeted heterostructures will be critical to controlling the reaction pathways for each of these strategies, and our list of potential constituents include piezoelectric (GeSe, SnSe), topological insulating (Bi2Se3, Bi2Te3), semiconducting (PbSe, MoSe2, SnSe2) and/or superconducting (NbSe2) layers. A rich collection of new materials with diverse and tunable emergent properties is anticipated.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 2010 年诺贝尔物理学奖获奖者是在具有二维 (2D) 结构的单层化合物中发现了块体化合物中不存在的新特性，由此产生了科学领域 - 2D 材料和 2D 堆叠层。随着理论学家提出新的奇特特性和实验学家发现单层和异质结构的新特性，异质结构材料呈指数级增长。目前，异质结构的制备是通过以下方法完成的。将块状材料切割至单层极限并按设计的顺序堆叠它们，这种方法仅限于可切割的块状化合物，因此需要新的合成方法来制备晶圆级异质结构，从而提供更广泛的选择。组成层，并提供对纳米结构的控制（组成层的堆叠顺序和厚度）。在该项目中，在材料研究部的固态和材料化学和陶瓷项目的支持下，俄勒冈大学的 David Johnson 博士和他的研究小组将开发新的合成方法来制备含有 2D 磁性成分层的异质结构，其结构和成分不像孤立的化合物那样热力学稳定。三种不同的策略，所有这些都使用前体正在测试与目标异质结构相匹配的目标成分分布，该研究项目为研究生提供了沉积技术、薄膜表征技术和二维异质结构中发生的物理现象方面的广泛技术背景。在各种未来职业（高科技行业、学术界或国家实验室）的实习将为研究生提供“试驾”未来职业的机会，同时扩大他们的知识基础，从而让本科生参与这项研究，从而提高他们的生产力。应用在课堂上学到的原理来解决研究挑战。 提供本科生研究机会是增加以科学为职业的学生数量和多样性的关键工具。俄勒冈大学材料研究部的项目，大卫·约翰逊博士和他的研究小组将开发合成方法来制备含有二维磁性成分层的异质结构，其结构和成分在热力学上不稳定，因为合成目标包括二硒化物。 (TSe2) 和岩盐结构的 Pb2+nT1+mSe3+n+m 层，其中 T = Cr、Mn、Fe 和 Ni 三种合成策略，使用具有目标局部成分的前体和一种控制成核和生长的纳米结构正在测试中，一种策略是制备一种前驱体，使一层通过受控成分的非晶层分离结晶为二维片材，以及交错非晶层的成分。相邻晶体层的结构将用于控制亚稳态成分层的成核和生长。第二种策略是通过控制局部成分来播种所需结构的成核。目标异质结构中的伴随成分对于控制每​​种策略的反应途径至关重要，我们的潜在成分列表包括压电材料（GeSe、SnSe）。 、拓扑绝缘层（Bi2Se3、Bi2Te3）、半导体层（PbSe、MoSe2、SnSe2）和/或超导层（NbSe2）。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。