Measuring the Electron Spectral Function by Angle-Resolved Photoemission

通过角分辨光电测量电子光谱函数

• 批准号: 9974401
• 负责人: Juan Carlos Campuzano
• 金额: $ 30.08万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9974401&HistoricalAwards=false
• 关键词: Measuring; Electron; Spectral; Function; Angle

9974401CampuzanoThe goal of this project is to determine the nature of the charge carriers in the high temperature superconductors using the technique of angle-resolved photoemission (ARPES). This spectral function represents the probability of adding or removing an electron from a many-body system. In these materials, the electrons strongly interact with one another and with other collective excitations such as spin waves. The spectral function provides very useful information about these interactions. Under suitable conditions, the spectral function can be manipulated to yield the self energy of the electrons, which is the quantity directly calculable by modern theories of strongly interacting many-body systems. This work aims to study the self-energy in the different states of high temperature superconductors. This project also seeks to understand how the Fermi surface changes shape when the material undergoes the superconducting transition. Recent work by this group has found the remarkable effect that electronic states at different momenta become gapped at different temperatures, leading to a break up of the Fermi surface into disconnected Fermi arcs which shrink with decreasing T, eventually collapsing to points in the superconducting ground state below Tc. This novel behavior, where the Fermi surface does not form a continuous contour in momentum space as in conventional metals, is unprecedented in that it occurs in the absence of long range order.%%%The high temperature superconductors are materials that carry current without any resistance when cooled to the temperature of liquid air. This research using the technique of angle-resolved photoemission (ARPES) is designed help reach an understanding of how electrons move in the high temperature superconductors to carry electrical current. These new materials are unlike all previously known materials in the way they conduct electricity. Now, 10 years after their discovery, the mechanisms are still not fully understood. This work aims to connect the physical quantities measured by ARPES to quantities measured using other techniques. As aconsequence, this project provides excellent research opportunities for graduate students who wish to work at the frontier of our understanding of new materials.***

9974401Campuzano本项目的目标是确定的性质的电荷载流子在高温超导体使用角分辨光电发射（ARPES）技术。这个光谱函数表示从多体系统中增加或移除一个电子的概率。在这些材料中，电子彼此之间以及与其他集体激发（如自旋波）发生强烈的相互作用。光谱函数提供了关于这些相互作用的非常有用的信息。在适当的条件下，光谱函数可以被操纵以产生电子的自能量，这是通过强相互作用多体系统的现代理论可以直接计算的量。本工作旨在研究高温超导体在不同状态下的自能。该项目还试图了解当材料经历超导转变时费米表面如何改变形状。该小组最近的工作发现了一个显著的效应，即不同动量的电子态在不同温度下会产生带隙，导致费米表面分裂成不连通的费米弧，这些费米弧随着T的减小而缩小，最终坍缩到低于Tc的超导基态中的点。这种新颖的行为，其中费米表面不像传统金属那样在动量空间中形成连续轮廓，是前所未有的，因为它发生在缺乏长程有序的情况下。高温超导体是当冷却到液态空气的温度时没有任何电阻地携带电流的材料。本研究利用角分辨光电子能谱（ARPES）技术，旨在帮助理解电子如何在高温超导体中运动以携带电流。这些新材料在导电方式上不同于所有以前已知的材料。现在，在他们发现10年后，其机制仍然没有完全理解。这项工作旨在将ARPES测量的物理量与使用其他技术测量的物理量联系起来。因此，该项目为希望在我们对新材料的理解的前沿工作的研究生提供了极好的研究机会。