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，由于其各种独特的物理性质，如磁性和超导性，长期以来一直被研究。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得到重视。由这些金属组成的氧化物在导电时表现出不同寻常的特性，使它们成为量子计算技术的有力候选者。本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称为分子束外延的技术，研究由两种不同元素组成的材料的不寻常行为，这些材料由原子尖锐的界面制成。通过在三明治结构中交替使用每种材料的层来产生重复的界面，研究的重点是制造一种能够多次展示界面特性的材料。通过两个外展项目，阿拉巴马州农村和服务不足地区的科学接触范围扩大到那些在日常生活中没有接触到科学的群体。研究者通过阿拉巴马监狱艺术与教育项目在阿拉巴马监狱教授关于物理和材料科学在新技术中的应用的年度研讨会，为非传统的学生在他们的康复过程中提供科学丰富和教育，这是其他方式无法获得的。研究人员还领导了一年一度的Gameday物理推广活动，在奥本大学校园内高度关注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比由3d元素组成的复合氧化物表现出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，预计会表现出高温超导性和其他出现的拓扑现象。这些特性使得4d和5d材料有望用作实现拓扑量子计算的材料。本课题通过杂化分子束外延的方法，系统地研究了几种候选的4d和5d络合物氧化物的合成。使用这种新方法，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，生产出更高质量的材料。对涌现界面现象的探索包括高温超导性、铁电性和拓扑电子态。通过合成由重复界面组成的超晶格薄膜，研究重点是在体膜中表现出界面现象的材料的开发。本项目为本科生提供了通过机器学习分析衍射和光谱数据来学习材料表征的教育经验。用于分析这些数据的计算代码为研究社区共享，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材料合成和表征的经验。这些经验有助于学生为集成电路和电子器件行业的材料研究工作做好准备。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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 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.