Tuning electronic instabilities in triangular surface lattices via subsurface doping

摘要：本项目旨在通过化学掺杂实验对单原子薄膜材料的电子性能进行可控修饰。所研究的薄膜系统由在硅衬底上排列成各种三角形图案的锡或铊原子组成。单原子锡层特别令人感兴趣，因为有可能通过化学掺杂获得具有奇异性质的新型电子材料，例如超导性。通过单原子铊薄膜的化学掺杂，可以获得奇异磁性。原子尺度上对量子力学机制的理解产生了这种涌现的电子行为，这对于推进一类新的电子材料作为硅的可能替代品至关重要，例如，用于信息技术的纳米电子器件。田纳西大学拟议的科学和支持基础设施为具有国际竞争力的研究生的教育和培训提供了良好的环境。一项将资助研究与本科教育相结合的严格计划正在实施，以提高物理专业的入学率。外展计划的目标是在著名的田纳西州州长科学与工程学校就读的二年级和初中学生。通过为所有这些年轻人提供独特的研究和教育经验，研究人员旨在吸引这些深刻的思想家和未来的决策者去攻读物理科学的高级学位。技术摘要：通过化学掺杂来控制复杂材料的电子特性，是推进复杂材料知识和实际应用的一个关键方面。对于一个严格的二维体系，化学掺杂不可避免地引入了结构紊乱，因为电离后的掺杂杂质成为二维电子体系的组成部分。该项目建立在早期NSF赞助的研究的主要成果之上，其中表面层或薄膜的孔掺杂是通过亚表面或？调制掺杂?。与复杂氧化物体系的研究类似，本研究旨在扩大空穴掺杂剂的浓度范围，将调制掺杂的概念扩展到n型物质，从而建立完整的电子相图。该策略被用于掺杂具有强莫特相关和强自旋轨道耦合的三角形表面晶格。前者中d波超导性的令人兴奋的可能性，以及后者中自旋密度波的不稳定性将作为掺杂水平的函数进行探索。该项目涉及超高真空薄膜生长，扫描隧道显微镜和光谱学，以及角度分辨光发射实验，所有这些都得到了外部合作者的理论支持。田纳西大学拟议的科学和支持基础设施为具有国际竞争力的研究生的教育和培训提供了良好的环境。一项将资助研究与本科教育相结合的严格计划正在实施，以提高物理专业的入学率。外展计划的目标是在著名的田纳西州州长科学与工程学校就读的二年级和初中学生。通过为所有这些年轻人提供独特的研究和教育经验，研究人员旨在吸引这些深刻的思想家和未来的决策者去攻读物理科学的高级学位。

Non-Technical Abstract:This project aims to controllably modify the electronic properties of monatomic thin film materials via chemical doping experiments. The thin film systems under investigation consist of tin or thallium atoms arranged in various triangular patterns on a silicon substrate. The monatomic tin layer is of particular interest because there is the potential to obtain novel electronic materials with possibly exotic properties, such as superconductivity via chemical doping. Exotic magnetism may be obtained through the chemical doping of monatomic thallium films. Atomic-scale understanding of the quantum mechanical mechanisms that give rise to such emergent electronic behavior is crucial in order to advance a new class of electronic materials as the possible replacement of silicon in, e.g., nano-electronic devices used in information technology. The proposed science and supporting infrastructure at The University of Tennessee provide an excellent setting for the education and training of internationally competitive graduate students. A rigorous plan for integrating sponsored research with undergraduate education is being implemented to boost enrolment in the physics major. The outreach program targets sophomore and junior high school students who are participating in the prestigious Tennessee Governor School for the Sciences and Engineering. By providing all of these young people with unique research and educational experiences, the investigators aim to entice these deep thinkers and future decision-makers to pursue an advanced degree in the physical sciences. Technical Abstract:A critical aspect for advancing knowledge and practical applications of complex materials is the ability to control their electronic properties via chemical doping. For a strictly two-dimensional system, chemical doping inevitably introduces structural disorder as the ionized dopant impurities become an integral part of the two-dimensional electron system. This project builds on the main accomplishments from earlier NSF sponsored research, in which hole doping of a surface layer or thin film was accomplished via subsurface- or ?modulation doping?. In analogy with studies on complex oxide systems, the investigations aim to widen the concentration range of the hole dopants and expand the modulation doping concept to n-type species, so as to establish a full electronic phase diagram. This strategy is being employed to dope triangular surface lattices with strong Mott correlations and strong spin-orbit coupling. The exciting possibilities of d-wave superconductivity in the former, and spin density wave instabilities in the latter will be explored as a function of the doping level. The project involves thin film growth in ultrahigh vacuum, scanning tunneling microscopy and spectroscopy, and angle-resolved photoemission experiments, all in conjunction with theoretical support from outside collaborators. The proposed science and supporting infrastructure at The University of Tennessee provide an excellent setting for the education and training of internationally competitive graduate students. A rigorous plan for integrating sponsored research with undergraduate education is being implemented to boost enrolment in the physics major. The outreach program targets sophomore and junior high school students who are participating in the prestigious Tennessee Governor School for the Sciences and Engineering. By providing all of these young people with unique research and educational experiences, the investigators aim to entice these deep thinkers and future decision-makers to pursue an advanced degree in the physical sciences.