Angle-Resolved Photoemission Experiments of Correlated Electronic Systems

技术：高分辨率角分辨光电发射（ARPES）将用于研究相关电子系统的电子结构，特别是巨磁阻（CMR）氧化物。这个项目过去的工作已经产生了关于CMR氧化物的最大的公开电子结构信息，现在使我们能够打开下一个层次甚至更深层次的问题，其中许多问题远远超出了锰矿。此外，与多个x射线和中子散射小组、光学小组和计算能带结构、相关效应和光电矩阵元素的理论小组的合作也非常重要和强大。该项目将主要利用伯克利先进光源的高分辨率光电发射光束线。该活动的一个重要组成部分是在光学、固体物理和同步辐射领域对学生进行跨学科训练。此外，P.I.领导一个REU（本科生研究经验）项目，并将继续包括本科生参与这项研究。非技术：爱因斯坦因光电效应获得诺贝尔奖，光电效应是指一个入射光子（单个光包）从固体中射出一个电子。这项技术已经成熟，可以说是固体中电子量子力学状态最强大的探测。我们将应用这项技术来研究一个特别有趣和潜在有用的效应，巨磁电阻或CMR。在CMR材料中，磁场的应用会引起电阻的“巨大”（高达11个数量级）变化，这些变化可能很多。我们的目标是了解这些材料中基本的量子力学相互作用，这是它们独特的电和磁特性的原因。该项目将主要利用伯克利先进光源的高分辨率光电发射光束线，该光源是美国卓越的同步辐射设备，可产生软x射线。该活动的一个重要组成部分是在光学、固体物理和同步辐射领域对学生进行跨学科训练。此外，P.I.领导一个REU（本科生研究经验）项目，并将继续包括本科生参与这项研究。

Technical: High resolution angle resolved photoemission (ARPES) will be used to study the electronic structure of correlated electron systems, particularly colossal magnetoresistive (CMR) oxides. Past work from this program has produced the largest body of published electronic structure information on CMR oxides which now allows us to open the next level of even deeper questions, many of which transcend far beyond the manganites. Also setting this work apart are very important and powerful collaborations with multiple x-ray and neutron scattering groups, an optics group, and a theory group for calculation of the band structure, correlation effects, and photoemission matrix elements. The program will principally utilize high resolution photoemission beamlines at the Advanced Light Source, Berkeley. An important component of the activity is the interdisciplinary training of students in the fields of optics, solid state physics, and synchrotron radiation. In addition, the P.I. leads an REU (Research Experience for Undergraduates) program and will continue to include undergraduates in this research.Non-Technical: Einstein received his Nobel prize for the photoelectric effect, in which an incident photon (individual packet of light) ejects an electron from a solid. This technique has matured into what is arguably the most powerful probe of the quantum-mechanical state of the electrons within a solid. We will apply this technique to study a particularly interesting and potentially useful effect, colossal magnetoresistance or CMR. In CMR materials, the application of a magnetic field induces "colossal" (up to 11 orders of magnitude) changes in electrical resistance which may be many. Our goal is to understand the basic quantum mechanical interactions in these materials that is responsible for their unique electrical and magnetic properties. The program will principally utilize high resolution photoemission beamlines at the Advanced Light Source, Berkeley, which is the nation's preeminent synchrotron radiation facility producing soft X-rays. An important component of the activity is the interdisciplinary training of students in the fields of optics, solid state physics, and synchrotron radiation. In addition, the P.I. leads an REU (Research Experience for Undergraduates) program and will continue to include undergraduates in this research.