Electron tunneling spectroscopy of the novel pairing state in the 1-1-5 heavy fermions and possible topological Kondo insulator YbB12

摘要：在本项目中，使用探索电子性质的技术研究凝聚态物理中的两个重要主题。首先，在超导状态下无耗散的电传输是一个基本的主题，这里通过研究一组超导体来确定超导的机制。其次，这个项目的另一半重点放在拓扑绝缘体上，这是一种新型的量子物质，在其表面具有受保护的导电状态。当相互作用很强时，这种新特性是如何出现的还不清楚。为了解决这一尚未解决的问题，本项目将隧道光谱应用于不同形式和静水压力下的多种候选材料。年轻一代的科学家，包括研究生和本科生，积极参与该项目，承担关键的实验活动，并接受培训，以获得专业技能，如书面和口头传播他们的工作。计划向代表性不足的群体伸出援助之手，并参与各种活动，重点是提高公众在STEM领域的识字率。技术摘要：本项目涉及凝聚态物理的两个前沿研究课题：重费米子超导体1-1-5族中的配对机制和相关拓扑材料中强相关与拓扑的相互作用。电子隧穿光谱用于揭示它们的关键光谱特性，这些特性对于微观理解底层物理是必不可少的。尽管重费米子超导体中涉及自旋涨落的配对机制被广泛接受，但重费米子1-1-5家族的关键实验特征仍然存在争议/缺失。由此产生的光谱信息有望导致加深理解强相关性和拓扑之间的相互作用。包括研究生和本科生在内的年轻一代科学家积极参与该项目，承担关键的实验活动，并接受书面和口头传播等专业技能的培训。参与该项目的所有人员都参与了提高公众在STEM领域素养的外展活动。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 Abstract: In this project, two important topics in condensed matter physics are studied using techniques that explore properties of electrons. First, transport of electricity without dissipation in a superconducting state is a fundamental topic addressed here by investigating a wide group of superconductors to determine the mechanism of superconductivity unambiguously. Second, the other half of this project focuses on topological insulators, a novel class of quantum matter harboring protected conducting states at their surfaces. How this novel property emerges is not yet understood when the interactions are strong. To tackle this unsolved problem, this project applies tunneling spectroscopy to multiple candidate materials in different forms and under hydrostatic pressure. Younger generation of scientists including graduate and undergraduate students are actively involved in this project by undertaking key experimental activities and trained to acquire professional skills such as written and verbal dissemination of their work. Outreach to underrepresented group is planned, as well as engagement in various activities focusing on elevating general public’s literacy in STEM fields.Technical Abstract: This project involves two forefront research topics in condensed matter physics: the pairing mechanism in the 1-1-5 family of heavy-fermion superconductors and the interplay between strong correlations and topology in correlated topological materials. Electron tunneling spectroscopy is employed to reveal their key spectroscopic properties that are essential for microscopic understanding of the underlying physics. Despite the widely accepted pairing mechanism involving spin fluctuations in heavy-fermion superconductors, key experimental signatures for the 1-1-5 family of heavy fermions remain controversial/missing. The resultant spectroscopic information is expected to lead to a deepened understanding of the interplay between strong correlations and topology. Younger generation of scientists including graduate and undergraduate students are actively involved in this project by undertaking key experimental activities and trained for acquiring professional skills such as written and verbal dissemination of their work. All personnel involved in this project participate in outreach activities to elevate general public’s literacy in STEM 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.