CAREER: Spin-Resolved Imaging of Correlated Electron Systems Including Cuprates and Pnictides

【非技术摘要】该职业奖资助一个复杂材料中电子自旋成像的项目。虽然金属中的电子各有各的事，几乎不相互作用，但在所谓的“强相关电子”材料中，电子的相互作用驱动着独特的特性，这些特性令人着迷，而且往往很有用。例如，所谓的高温超导体在经济可行的温度下不损耗地导电；多铁性材料允许使用磁场进行电子数据存储和使用电场进行磁性数据存储；重费米子物质的电子行为是其实际质量的数千倍；被称为石墨烯的简单碳片可以让电子快速移动，就好像它们根本没有质量一样。这些材料的共同点是它们的电子相互作用强烈，而人们对这些相互作用知之甚少。该项目将采用自旋极化扫描隧道显微镜，以原子分辨率测量电子自旋的能量和位置，从超导体开始。该项目还将利用这项技术教育三个值得关注的群体：哈佛大学的学生将从扫描隧道显微镜的新本科课程中受益；当地小学的孩子们将被邀请参观一个正在工作的科学实验室，观看真实的电子；感兴趣的市民可以浏览一个丰富多彩的网站，解释正在调查的各种令人着迷的材料。【技术摘要】该职业奖资助了一个项目，该项目对铜酸盐和镍酸盐等高温超导体中的电子自旋进行成像。这些奇异材料的共同特征是它们的电子相互作用强烈，并且没有广泛成功的理论语言来描述这些所谓的“相关电子材料”。通过对电子电荷相互作用成像的各种方法已经取得了很大的进步，但是由于缺乏有效的工具来对电子自旋相互作用成像，人们的理解受到了限制。本项目将采用低温自旋极化扫描隧道显微镜，以原子分辨率测量电子态的自旋分辨密度。特别的是，将对自旋相互作用的孵出态和杂化态进行比较，这是目前已知的仅有的两种高温超导体，分别于1986年和2008年发现。该项目还将利用这种自旋成像技术来教育三个值得关注的群体：哈佛大学的学生将从扫描隧道显微镜的新本科课程中受益；当地小学的孩子们将被邀请去参观一个真实电子成像的科学实验室；感兴趣的公民可以浏览一个丰富多彩的网站，解释正在调查的各种强相关材料。

NON-TECHNICAL ABSTRACTThis CAREER award funds a project to image electron spins in complexmaterials. Although electrons in metals mind their own business, barelyinteracting with each other, in so-called 'strongly correlated electron'materials the interactions of electrons drive unique properties that arefascinating and often useful. For example, so-called high-Tcsuperconductors carry electricity without loss at economically feasibletemperatures; multi-ferroic materials allow electronic data storage usinga magnetic field and magnetic data storage using an electric field; heavyfermion materials boast electrons behaving with thousands of times theiractual mass; simple sheets of carbon called graphene allow electrons tozip along as if they had no mass at all. These materials have in commonthat their electrons interact strongly, and that those interactions arepoorly understood. This project will employ a spin-polarized scanningtunneling microscope to measure the energies and locations of electronspins with atomic resolution, starting with superconductors. The projectwill also use this technology to educate three deserving groups: Harvardstudents will benefit from a new undergraduate course on scanningtunneling microscopy; local elementary school children will be invited tosee a working science lab viewing real electrons; interested citizens willbe able to browse a colorful website explaining the fascinating variety ofmaterials under investigation.TECHNICAL ABSTRACTThis CAREER award funds a project to image electron spins in high-Tcsuperconductors, both cuprates and pnictides. The common feature to theseexotic materials is that their electrons interact strongly, and there isno broadly successful theoretical language to describe these so-called'correlated electron materials'. Great strides have been made throughvarious methods of imaging the interactions of electron charges, butunderstanding has been limited by the lack of effective tools to image theinteractions of electron spins. This project will employ a lowtemperature spin-polarized scanning tunneling microscope to measure thespin-resolved density of electronic states with atomic resolution. Inparticular, a comparison will be made between spin interactions incuprates and pnictides, the only two known families of high-Tcsuperconductors, discovered in 1986 and 2008. The project will also usethis spin imaging technology to educate three deserving groups: Harvardstudents will benefit from a new undergraduate course on scanningtunneling microscopy; local elementary school children will be invited tosee a working science lab imaging real electrons; interested citizens willbe able to browse a colorful website explaining the fascinating variety ofstrongly correlated materials under investigation.