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

现代电子学依赖于晶体半导体材料之间精确控制的界面。实现这一目标仍然是一项挑战。该项目由材料研究部的固态和材料化学计划支持，研究从根本上制造磁性材料的这种界面并以尽可能小的长度尺度（原子分辨率）控制它们的新方法。该项目专注于一类称为Heusler化合物的材料，探索在原子级薄屏障材料上单晶生长的机制。这些材料在节能的磁性和热电器件的应用也进行了测试。研究工作与中学生课后讲习班相结合。从原子到iPhone：材料科学及其在日常生活中的应用。“是一个通过智能手机这一常见应用的透镜，让年轻学生参与材料科学和工程主题的研讨会。主要研究者和他的小组在戴恩县男孩女孩俱乐部与SCIENCountErs项目一起开展这项工作。该项目由材料研究部的固态和材料化学计划支持，旨在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，跨Heusler/半导体界面的相互扩散抑制了这些实现，因为需要原子尖锐和稳定的外延界面。该项目通过使用石墨烯等原子级薄的阻挡材料来解决这些挑战，其中阻挡材料用作（1）扩散阻挡层，（2）用于薄膜和衬底之间的外延对准的透明去耦层，以及（3）用于跨界面有效传输电荷和自旋的隧道阻挡层。通过配对高度控制的Heusler合成分子束外延（MBE）与原位光谱工具，模型实验被用来揭示机制货车德瓦尔斯介导的外延和开发方法的原子控制制造的Heusler接口。从研究组成部分的基本见解被集成到“原子到iPhone”研讨会的真实的生活演示中，并被集成到由主要研究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及相关领域的职业生涯提供了培训基础。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值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.