The Role of Defects in Two-Dimensional Phase Transitions

这一个人研究人员奖将为一个项目的高级研究员提供资金，该项目旨在调查缺陷在二维相变中的作用。对称性、维度和无序的概念都是描述相变的核心。人们普遍认为，缺陷可以在相变中发挥关键作用，特别是在降维过程中。变温扫描隧道显微镜(STM)可获得的原子分辨率与在表面上不平衡地生长人工结构的二维和一维组态的能力相结合，有望改变我们在降维相变中考虑缺陷作用的方式。该项目将利用变温扫描隧道显微镜，呈现作为温度函数的表面原子和电子分布的空间图像。表面结构和晶格动力学将通过弹性和非弹性电子散射以及表面x射线散射来确定。表面磁性将利用最新设计的八极超导磁体，通过线性和非线性磁光克尔旋转相结合的方式进行探测。从本科生到研究生阶段的年轻科学家将在学术、工业和政府实验室接受与未来职业相关的技术培训。这个个人研究人员奖将为一个项目提供资金，该项目旨在从两个维度调查材料系统相变中缺陷或缺陷的基本作用。人们普遍认为，缺陷可以在相变中发挥关键作用，特别是在降维过程中。许多潜在的技术设备利用了给定材料中的相变特性。随着器件尺寸的减小，了解缺陷对这些降维材料相变的影响是很重要的。这项研究计划的影响将从两个方面感受到。首先，这些实验和由此产生的概念可能会改变我们在降维中思考相变的方式。其次，也是最重要的是，在支持我国纳米技术国家议程的一个领域，对本科生、研究生和研究生的青年科学家进行培训。

This individual investigator award will provide funds to a senior researcher for a project to investigate the role of defects in two-dimensional phase transitions. The concepts of symmetry, dimensionality, and disorder all are central to the description of phase transitions. It is generally recognized that defects can play a critical role in phase transitions, especially in reduced dimensionality. The combination of the atomic resolution available with the variable-temperature scanning tunneling microscope (STM) coupled with the ability to grow artificially structured two and one-dimension configurations out of equilibrium on a surface promises to change the way we think about the role of defects in phase transitions in reduced dimensionality. This project will utilize a variable-temperature STM, which renders spatial images of the atomic and electronic distributions at the surface as a function of temperature. Surface structure and lattice dynamics will be determined with elastic and inelastic electron scattering as well as surface x-ray scattering. Surface magnetism will be probed with a combination of linear and non-linear magneto-optical Kerr rotation utilizing a newly designed octapole superconducting magnet. Young scientists from the undergraduate through the post-graduate levels will be trained in techniques relevant to future careers in academe, industry, and government laboratories.%%%This individual investigator award will provide funds to a senior researcher for a project to investigate the fundamental role of imperfections or defects in phase transitions for material systems in two dimensions. It is generally recognized that defects can play a critical role in phase transitions, especially in reduced dimensionality. Many potential technological devices utilize the properties of a phase transition in a given material. As the size of devices become smaller, it is important to understand the effect of defects on the phase transitions of these materials of reduced dimension. The impact of this research program will be felt on two fronts. First, these experiments, and the concepts that come from them, may change the way we think about phase transitions in reduced dimensionality. Secondly, and most importantly, is the training of young scientists at the undergraduate, graduate and post-graduate levels in an area supporting our national agenda on nanotechnology.***