CAREER: Topological Phenomena in 4d and 5d Complex Oxide Interfaces and Superlattices Grown by Hybrid Molecular Beam Epitaxy

非技术描述：金属氧化物薄膜，如氧化亚铁和二氧化钛，长期以来一直被研究，因为它们具有各种独特的物理性能，如磁性和超导电性。然而，只是在过去的几年里，对由元素周期表中较低的金属元素组成的氧化物的研究才获得了突出的地位。由这些金属组成的氧化物在导电时表现出不同寻常的性质，使它们成为量子计算技术的有力候选者。该项目的重点是合成由元素周期表第四行和第五行元素组成的氧化物薄膜。研究人员正在使用一种名为分子束外延的技术，研究由两种不同元素组成的材料产生的不寻常行为，这些元素具有原子上尖锐的界面。通过在夹层结构中交替每种材料的层来产生重复的界面，这项研究的重点是制造一种能够多次展示界面属性的材料。通过两个外展计划，在阿拉巴马州农村和服务不足地区接触科学的机会被扩大到日常生活中没有接触到科学的群体。这位调查员通过阿拉巴马州监狱艺术和教育项目在阿拉巴马州监狱教授年度研讨会，内容是将物理和材料科学应用于新技术，在非传统学生的康复期间为他们提供其他方式无法获得的科学丰富和教育。研究人员还领导一年一度的Gameday物理推广活动，在奥本大学校园内观看人数众多的足球比赛中，进行科学演示，并向广泛而多样化的观众介绍物理研究。技术细节：由4d和5d过渡金属组成的复合氧化物表现出比由3D元素组成的复合氧化物明显更高的自旋-轨道耦合。这些材料在外延薄膜异质结构和超晶格中形成时，已被预测表现出高温超导电性和其他新出现的拓扑现象。这些性质使得4d和5d材料有望用作实现拓扑量子计算的材料。在本项目中，系统地研究了几种候选的4d和5d复合氧化物的合成。使用这种新的方法，金属-有机前驱体取代了过渡金属的传统元素来源，使合成更容易，并生产出更高质量的材料。对新出现的界面现象的探索包括高温超导、铁电和拓扑电子态。通过合成由重复界面组成的超晶格薄膜，这项研究的重点是开发在大块薄膜中显示界面现象的材料。该项目为本科生提供了通过机器学习分析衍射和光谱分析数据来学习材料表征的教育经验。分析这些数据的计算代码被共享给研究团体，以推进电影合成的实时分析。研究生研究人员在实验室和世界各地的用户设施中获得了材料合成和表征方面的经验。这些经历有助于学生为在集成电路和电子设备行业从事材料研究做好准备。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 DESCRIPTION: Thin films of metal oxides such as ferrous oxide and titania have long been studied for their various unique physical properties, such as magnetism and superconductivity. It is only in the past few years, however, that research in oxides comprised of metallic elements lower in the periodic table has gained prominence. Oxides composed of these metals exhibit unusual properties when they conduct electricity making them strong candidates for use in quantum computation technologies. This project focuses on the synthesis of oxide thin films comprised of elements in the fourth and fifth rows of the periodic table. Researchers are studying the unusual behavior derived from materials comprised of two different elements made with atomically sharp interfaces using a technique called molecular beam epitaxy. By alternating layers of each material in a sandwich structure to produce repeating interfaces, the research focuses on making a material that exhibits the properties of the interface many times over. Through two outreach programs, exposure to science in rural and underserved areas of Alabama is broadened to groups that are not introduced to science in their daily lives. The investigator teaches annual seminars in Alabama prisons through the Alabama Prison Arts and Education Project about the applications of physics and materials science to new technologies, offering non-traditional students scientific enrichment and education during their rehabilitation that is not otherwise available. The researchers also lead the annual Gameday Physics outreach event to perform science demonstrations and introduce physics research to a broad and diverse audience at highly-attended football games on the Auburn University campus. TECHNICAL DETAILS: Complex oxides comprised of 4d and 5d transition metals exhibit significantly higher spin-orbit coupling than those comprised of 3d elements. These materials have been predicted to exhibit high temperature superconductivity and other emergent topological phenomena when formed in epitaxial thin film heterostructures and superlattices. These properties make 4d and 5d materials promising for use as materials to enable topological quantum computation. In this project, systematic studies of synthesis of several candidate 4d and 5d complex oxides via hybrid molecular beam epitaxy are performed. Using this novel approach, a metal-organic precursor replaces the traditional elemental source for the transition metal, enabling easier synthesis and producing higher quality materials. Exploration of emergent interfacial phenomena includes high-temperature superconductivity, ferroelectricity, and topological electronic states. By synthesizing superlattice films comprised of repeating interfaces, the research focuses on the development of materials that exhibit interfacial phenomena in a bulk film. This project provides educational experiences for undergraduate students to learn about materials characterization through machine learning analysis of diffraction and spectroscopy data. Computational codes to analyze such data are shared for the research community to advance real-time analysis of film synthesis. Graduate student researchers gain experience in materials synthesis and characterization in the lab and at user facilities around the world. Such experiences help prepare students for careers in materials research in the integrated circuit and electronic device industry.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.