Iron Pyrite {100}: Investigation into an Electronically Frustrated Material

非技术描述：黄铁矿是地球上最丰富的矿物之一。黄铁矿还具有一些非常适合光电子学和储能应用的关键物理性质。但大量的测量表明，块状和纳米晶黄铁矿的电子输运和光学性质限制了有效的器件开发。这些限制的根本原因仍然深陷不确定性之中，但最近的工作确实表明，铁黄铁矿表面和界面上的缺陷结构和化学成分是首要的重要因素。该研究项目是一项协同的实验和理论工作，旨在提供对黄铁矿及其表面物理和化学的全面了解。在这项研究活动的同时，计划开展一项合作的K-6外联活动，以提高对材料科学的认识，并向年轻一代灌输对科学方法的兴趣。将与当地学校的K-6课程协调开发和传播一系列动手材料科学模块，以促进他们在未来几年的科学计划。技术描述：最近观察到的铁硫铁矿纳米立方体胶体中不寻常的光电现象直接将其独特的{100}表面缺陷结构与周围的化学环境联系起来。本研究项目的实验部分旨在通过胶体、薄膜和单晶样品的界面表征和定向化学修饰来验证表面相互作用模型。高分辨率的表面敏感光谱，结合跨越广泛温度范围的磁测量和电子测量，被应用于黄铁矿的固有和工程表面结构，以建立全面的结构/性能关系。一个平行的理论工作系统地检查了铁黄铁矿的块体和表面激发态的性质，使用了一些可以完成的最详细的电子结构计算。为此，GW方法、Bethe-Salpeter和含时密度泛函理论将光学和输运性质与其微观起源联系起来。特别是，系统地研究了电子-声子耦合的表现，并与实验观测结果进行了比较。

Non-technical Description: Iron pyrite is one of the most abundant minerals on the planet. Iron pyrite also has some key physical properties well suited to optoelectronics and energy storage applications. But numerous measurements indicate that the electronic transport and optical properties of bulk and nanocrystalline iron pyrite limit effective device development. The fundamental causes of these limitations remain mired in uncertainty, but recent work does suggest that defect structure and chemistry on the surfaces and interfaces of iron pyrite are of primary importance. This research project is a synergistic experimental and theoretical effort designed to provide a comprehensive understanding of iron pyrite and its surface physics and chemistry. In conjunction with this research activity, a collaborative K-6 outreach effort is planned to increase awareness of materials science, and to instill an interest in scientific methods in the younger generation. A series of hands-on materials science modules will be developed and disseminated in coordination with K-6 curricula at local schools in order to further their science programs for years to come.Technical Description: Recent observations of unusual optoelectronic phenomena in iron pyrite nanocube colloids directly link its unique {100} surface defect structure to the surrounding chemical environment. The experimental component of this research project aims to validate the surface interaction model through interface characterization and directed chemical modification of colloidal, thin film and single crystal samples. High-resolution, surface-sensitive spectroscopy, in conjunction with magnetic and electronic measurements that span a broad range of temperatures, are applied to iron pyrite's intrinsic and engineered surface structure to build a comprehensive structure/property relationship. A parallel theoretical effort systematically examines the nature of the excited states for iron pyrite's bulk and surfaces using some of the most detailed electronic structure calculations that can be done. For these purposes, the GW method, Bethe-Salpeter and time-dependent density functional theory relate optical and transport properties to their microscopic origins. In particular, the manifestations of electron-phonon couplings are systematically examined and compared to experimental observations.