CAREER: Van der Waals-mediated epitaxy of Heusler compounds through properties-selective, atomically thin barriers

非技术概述现代电子学依赖于晶体半导体材料之间精确控制的接口。实现这一目标仍然是一项挑战。该项目在材料研究部固态和材料化学计划的支持下，从根本上研究了制造这种磁性材料界面并将其控制在尽可能小的长度尺度(原子分辨率)的新方法。该项目专注于一类名为Heusler化合物的材料，探索在原子薄的阻挡材料上生长单晶的机制。还测试了这些材料在节能磁器件和热电器件中的应用。这项研究工作与中学生的课后研讨会相结合。“从原子到iPhone：材料科学及其在日常生活中的应用。”是一个研讨会，通过智能手机这一常见应用程序的镜头，让年轻学生参与材料科学和工程主题的研究。首席调查员和他的小组与戴恩县男孩和女孩俱乐部的SCIENCountErs方案一起开展了这方面的工作。技术概述该项目得到材料研究部固态和材料化学计划的支持，旨在从根本上发现和开发控制离子、电荷和自旋在Heusler界面上传输的新方法。Heusler化合物长期以来一直被认为是半导体自旋电子学的理想材料，也是发现和操纵物质拓扑量子态的平台。然而，Heusler/半导体界面上的互扩散阻碍了这些实现，因为需要原子锐利和稳定的外延界面。该项目通过使用原子薄的势垒材料(如石墨烯)来应对这些挑战，其中势垒材料用作(1)扩散势垒，(2)用于薄膜和衬底之间外延对准的透明去耦合层，以及(3)用于在界面上有效地传输电荷和自旋的隧道势垒。通过将分子束外延(MBE)的高控制Heusler合成与原位光谱工具相结合，模型实验被用来揭示Van der Waals介导的外延的机理，并开发原子控制的Heusler界面的制备方法。来自研究部分的基本见解被整合到“从原子到iPhone”研讨会的真实演示中，并被整合到由首席调查员教授的本科生和研究生课程中。本科生和研究生的第一手研究经验为STEM和相关领域的职业提供了培训基础。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical summary Modern electronics rely on precisely controlled interfaces between crystalline semiconducting materials. Achieving this remains a challenge. This project, supported by the Solid State and Materials Chemistry Program in the Division of Materials Research, researches fundamentally new ways to fabricate such interfaces of magnetic materials and control them at the smallest length scale possible (atomic resolution). Focusing on a class of materials called Heusler compounds, the project explores the mechanisms for single-crystalline growth on atomically thin barrier materials. Application of these materials in energy-efficient magnetic and thermoelectric devices is also tested. The research efforts are integrated with an after-school workshop for middle-school students. "From atoms to iPhone: the science of materials and their applications in everyday life." is a workshop that engages young students in materials science and engineering topics through the lens of a common application, the smartphone. The principle investigator and his group carry out work with the SCIENCountErs program at the Boys and Girls Club of Dane County on this. Technical summaryThis project is supported by the Solid State and Materials Chemistry Program in the Division of Materials Research and aims to uncover and develop fundamentally new ways to control the transmission of ions, charge, and spins across Heusler interfaces. Heusler compounds have long been proposed as ideal materials for semiconductor spintronics and a platform for discovery and manipulation of topological quantum states of matter. However, interdiffusion across the Heusler/semiconductor interface has inhibited these realizations, since atomically sharp and stable epitaxial interfaces are required. This project addresses these challenges through the use atomically thin barrier materials such as graphene, where the barrier material serves as (1) a diffusion barrier, (2) a transparent decoupling layer for epitaxial alignment between film and substrate, and (3) a tunnel barrier for efficient charge and spin transport across the interface. By pairing highly controlled Heusler synthesis by molecular beam epitaxy (MBE) with in-situ spectroscopic tools, model experiments are being used to reveal the mechanisms for Van der Waals-mediated epitaxy and develop methods for the atomically controlled fabrication of Heusler interfaces. Fundamental insights from the research component are integrated into real life demonstrations for the "Atoms to iPhone" workshop and integrated into undergraduate and graduate courses taught by the principle investigator. First hand research experiences for undergraduate and graduate students provide a training ground for careers in STEM and related fields.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.