CAREER: Excitonic condensation in double-layer graphene: phases, transport and photoluminescence properties, and the BCS-BEC crossver.

职业：双层石墨烯中的激子凝聚：相、传输和光致发光特性以及 BCS-BEC 交叉。

• 批准号: 1054020
• 负责人: Yogesh Joglekar
• 金额: $ 40万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1054020&HistoricalAwards=false
• 关键词: CAREER; Excitonic; condensation; double; layer

TECHNICAL SUMMARYThis CAREER award supports theoretical research that explores the phases, collective excitations, and transport and photoluminescence signatures of excitonic condensates in double-layer graphene and related systems. Using momentum-space mean-field analysis, the complementary real-space tight-binding method, and the effective action approach, the PI will focus on the following open questions:1) What are the transport and photoluminescence properties of uniform and crystalline excitonic condensates? 2) How do electronic screening, magnetic field, and the surface curvature affect them? 3) What are the signatures of BEC-BCS crossover in (non-uniform) condensates? 4) What are the differences between the results for a double-layer graphene system and other two-dimensional systems? The educational and outreach component of the proposal involves the training and mentoring of a postdoctoral fellow, a graduate student, as well as undergraduate and high school students. The PI will involve high school and undergraduate students in research and scholarly activities that emphasize the duality between textbook learning and research. The research will be translated into self-contained pedagogical modules that can be incorporated into the undergraduate curriculum. The hands-on research experience for K-12 students will be complemented with periodic dissemination of exciting discoveries in science through a website and school-visits.NON-TECHNICAL SUMMARYThis CAREER award supports theoretical research that explores the possibilities and various properties of "excitonic condensates" in a relatively new class of materials. When light interacts with semiconductors or insulators and excites an electron from an occupied quantum state to an unoccupied one leaving behind an effective positive charge called the "hole", the electrostatic interaction between the negatively charged electron and the positively charged hole results in the formation of a bound state of these two entities called the "exciton". Due to quantum mechanical laws, it is possible for excitons to condense into the same lowest-energy state or form a liquid-like state in which they can flow without any viscosity, thereby forming "excitonic condensates". While such condensates are technologically important because they make zero-resistance electronic transport and coherent sources of light possible, progress towards their realization has been has been hampered due to materials whose properties are not widely tunable. Recently, a two-dimensional honeycomb network of carbon atoms, called graphene, has emerged as an exceptionally versatile, clean, and tunable electronic material. It is believed that graphene is a promising candidate for the realization of excitonic condensates. The PI will investigate the possibilities of excitonic condensation in a system of two layers of graphene stacked on top of another under various circumstances, and predict their signatures in electrical transport and light-emission measurements. The research will also address fundamental questions about excitonic condensates, and the results are expected to be applicable to a wide variety of systems. The educational and outreach component of the proposal involves the training and mentoring of a postdoctoral fellow, a graduate student, as well as undergraduate and high school students. The PI will involve high school and undergraduate students in research and scholarly activities that emphasize the duality between textbook learning and research. The research will be translated into self-contained pedagogical modules that can be incorporated into the undergraduate curriculum. The hands-on research experience for K-12 students will be complemented with periodic dissemination of exciting discoveries in science through a website and school-visits.

该职业奖支持理论研究，探索双层石墨烯和相关系统中激子凝聚物的相，集体激发，传输和光致发光特征。使用动量空间平均场分析，互补实空间紧束缚方法和有效作用量方法，PI将专注于以下开放性问题：1）均匀和结晶激子凝聚体的输运和光致发光性质是什么？2)电子屏蔽、磁场和表面曲率如何影响它们？3)（非均匀）凝聚体中BEC-BCS交叉的特征是什么？4)双层石墨烯系统和其他二维系统的结果有什么不同？该提案的教育和外联部分涉及培训和指导一名博士后研究员、一名研究生以及本科生和高中生。 PI将涉及高中和本科学生的研究和学术活动，强调教科书学习和研究之间的二元性。这项研究将转化为自成一体的教学模块，可以纳入本科课程。K-12学生的实践研究经验将通过网站和学校访问定期传播令人兴奋的科学发现。非技术总结该职业奖支持理论研究，探索相对较新的一类材料中“激子凝聚物”的可能性和各种性质。当光与半导体或绝缘体相互作用并将电子从占据的量子态激发到未占据的量子态，留下称为“空穴”的有效正电荷时，带负电的电子和带正电的空穴之间的静电相互作用导致形成这两个实体的束缚态，称为“激子”。 由于量子力学定律，激子有可能凝聚成相同的最低能量状态或形成类液体状态，在这种状态下它们可以流动而没有任何粘度，从而形成“激子凝聚物”。 虽然这种凝聚体在技术上很重要，因为它们使零电阻电子传输和相干光源成为可能，但由于材料的性质不能广泛调节，实现它们的进展受到阻碍。最近，碳原子的二维蜂窝网络，称为石墨烯，已经成为一种非常通用，清洁和可调的电子材料。石墨烯被认为是实现激子凝聚体的有希望的候选者。PI将研究在各种情况下在两层石墨烯堆叠在另一层石墨烯上的系统中激子凝聚的可能性，并预测它们在电传输和发光测量中的特征。这项研究还将解决有关激子凝聚的基本问题，预计结果将适用于各种各样的系统。该提案的教育和外联部分涉及培训和指导一名博士后研究员、一名研究生以及本科生和高中生。 PI将涉及高中和本科学生的研究和学术活动，强调教科书学习和研究之间的二元性。这项研究将转化为自成一体的教学模块，可以纳入本科课程。K-12学生的实践研究经验将通过网站和学校访问定期传播令人兴奋的科学发现。