CAREER: Emergent quantum phenomena in epitaxial thin films of topological Dirac semimetal and its heterostructures

职业：拓扑狄拉克半金属及其异质结构外延薄膜中的量子现象

• 批准号: 2339309
• 负责人: JYOTI KATOCH
• 金额: $ 68.15万
• 依托单位: Carnegie-Mellon University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-06-01 至 2029-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2339309&HistoricalAwards=false
• 关键词: CAREER; Emergent; quantum; phenomena; epitaxial

Nontechnical description:Topological phases of matter have attracted great attention in condensed matter physics due to their rich physics and possible revolutionary technological applications. Three-dimensional topological Dirac semimetals are of great interest due to their intriguing electronic band structure and are an ideal platform to realize emergent quantum phases, dissipationless transmission of electrons, efficient generation of spin current for spintronics, and advanced quantum device concepts such as the topological field effect transistor. The goal of this research project is to explore emergent topological phenomena in a three-dimensional topological Dirac semimetal as tuned by film thickness, external electric field, and magnetic interactions. The principal investigator and research team plans to synthesize high quality epitaxial thin films of a topological Dirac semimetal candidate, Na3Bi, and its heterostructures with magnetic insulators using molecular beam epitaxy. Employing in-operando nano-focused angle-resolved photoemission spectroscopy, the research team plans to directly probe, with no assumptions, the complex electronic band structure that is ultimately responsible for novel phenomena in this class of quantum materials. This project plans to support the doctorate dissertation of a graduate student, through training on different experimental techniques, critical thinking and solving complex research problems. The principal investigator also plans to provide research experience for undergraduate students in her lab every summer, for multiple years from a minority serving institution. The recruitment of the undergraduate students is facilitated through the existing tie-ups with the minority serving institutions. By taking advantage of this research program, the principal investigator proposes to design and implement a new advanced lab course to provide hands-on lab experience to students on research-grade equipment. Also, the plans to develop educational initiatives for a diverse population including an outreach program targeted towards middle and high school students belonging to underrepresented minorities in southwestern Pennsylvania. Technical description:The principal investigator proposes a comprehensive research project to study emergent quantum phenomena in epitaxial thin films of a topological Dirac semimetal and its heterostructures. This research is enabled by a unique home-built ultrahigh vacuum cluster system comprising of experimental capabilities of molecular beam epitaxy, in-situ thin film patterning, and in-situ cryogenic magnetotransport, which allows the research team to synthesize and measure thin films of a topological Dirac semimetal in pristine conditions. The research team plans to utilize molecular beam epitaxy to obtain high quality epitaxial thin films of Na3Bi and its heterostructures with magnetic insulators. The research team plans to employ quantum transport measurements to study thickness dependent non-trivial to trivial band gap insulator transitions, electric field controlled topological phases, and T-broken topological states in thin films of Na3Bi with integrated top and bottom electrostatic gates. In addition, the research team plans to utilize a state-of-the-art nano-focused in-operando angle-resolved photoemission spectroscopy with sub-100 nm spatial resolution to measure the Fermi level dependent (using integrated electrostatic back gate) topological band structure of Na3Bi thin films and their devices.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.

非技术描述：物质的拓扑阶段由于其丰富的物理学和可能的革命性技术应用而引起了凝结物理物理学的极大关注。三维拓扑狄拉克半法值引起了人们的极大兴趣，因为它们引人入胜的电子带结构，是实现新兴量子相位，无需耗散电子传输，有效地生成Spintronics的自旋电流以及高级量子设备概念（例如拓扑场效应晶体管）的理想平台。该研究项目的目的是在三维拓扑狄拉克半学中探索新兴的拓扑现象，并由膜厚度，外部电场和磁相互作用调节。首席研究员和研究团队计划使用分子束外延和磁性绝缘体合成拓扑狄拉克半学候选及其异质结构的高质量外延薄膜。研究小组采用以纳米为中心的角度分辨光发射光谱谱图，计划直接探测没有假设，这是最终负责此类量子材料中新现象的复杂电子带结构。该项目计划通过培训不同的实验技术，批判性思维和解决复杂的研究问题来支持研究生博士学位论文。首席研究人员还计划每年夏天在她的实验室中为本科生提供研究经验，从少数派服务机构开始多年。通过与少数派服务机构的现有合作，促进了本科生的招募。通过利用该研究计划，首席研究人员建议设计和实施新的高级实验室课程，以在研究级设备上为学生提供动手实验室经验。此外，计划针对各种各样的人口制定教育计划，包括针对宾夕法尼亚州西南部代表性不足少数民族的中学和高中生的外展计划。 技术描述：主要研究者提出了一个全面的研究项目，以研究拓扑狄拉克半学及其异质结构的外延薄膜中的新兴量子现象。这项研究由独特的自制超高真空集群系统组成，该系统包括分子束外延，原位薄膜薄膜图案和原位低温磁通转运的实验能力，这使研究团队可以合成和测量拓扑中的dirac半学条件下的薄膜。研究小组计划利用分子束外延，以获取具有磁绝缘体的Na3bi及其异质结构的高质量外延薄膜。研究小组计划采用量子运输测量值来研究厚度，依赖于琐碎的带隙绝缘子过渡，电场控制拓扑阶段以及在NA3BI的薄膜中具有集成顶部和底部静电门的T-BROKEN拓扑状态。此外，研究团队计划利用以亚100 nm的空间分辨率来利用以纳米为中心的纳米内部内部分解的光发射光谱，以衡量费米水平依赖性（使用集成的静电门（使用集成的静电门）（使用NA3BI薄膜及其设备的拓扑结构）使用NA3BI的拓扑结构。智力优点和更广泛的影响审查标准。