Electrostatic Charging Effects in Perovskite Oxides

w：\awards\awards96\*.doc 9623889 Xi 本项目主要研究载流子掺杂对钙钛矿材料的绝缘体-金属转变以及电子和磁性的影响 氧化物 这 表现出强 电子-电子关联 所使用的技术是静电充电，其中载流子密度在场效应晶体管状结构中以电学方式改变，而不引入无序、晶格 变形或结构相变。 该项目的一个目标是在高温超导铜酸盐样品中诱导超导性，这些样品最初不是超导的，并研究绝缘体-超导体相变的载流子密度依赖性和在此过程中的输运性质。该项目的长期目标是将静电充电作为研究具有强电子-电子相关性的钙钛矿氧化物系统中掺杂效应的重要工具。 金属氧化物是一类具有高温超导和巨磁阻等多种新颖性质的材料。在这些材料中掺杂电子电荷载流子，其中电子彼此强烈相互作用，是理解这些性质的关键。 然而，通常的化学掺杂方法是 总是伴随 通过 障碍 有时 结构 相变 该项目使用不同的方法研究掺杂效应，即静电充电， 其在电学上改变载流子密度而不引入其它效应。 该项目的目标之一是通过向非超导铜酸盐样品中加入电荷载流子将其转变为超导体。长期目标是将静电荷作为研究具有强电子-电子关联的金属氧化物的重要工具，这对于先进的超导和磁阻电子器件具有潜在的重大科学和技术意义。 ***

w:\awards\awards96\*.doc 9623889 Xi This project studies carrier doping effects on the insulator- metal transition and the electronic and magnetic properties of perovskite oxides which exhibit strong electron-electron correlations. The technique used is electrostatic charging, in which the carrier density is changed electrically in a field- effect transistor-like structure without introducing disorder, lattice distortion or a structural phase transition. One objective of the project is to induce superconductivity in high temperature superconducting cuprate samples which are originally not superconducting and study the carrier density dependence of the insulator-super-conductor phase transition and transport properties in this process. A long-term goal of this project is to establish electrostatic charging as an important tool in the research of doping effects in perovskite oxide systems with strong electron-electron correlations. %%% Metal oxides are a class of materials with a wide variety of novel properties such as high temperature superconductivity and colossal magneto-resistivity. Electron charge carrier doping in these materials, in which electrons interact strongly with each other, is the key to the understanding of these properties. However, the usual approach of chemical doping is always accompanied by disorder and sometimes structural phase transitions. This project studies the doping effects using a different approach, i.e. the electrostatic charging, which changes the carrier density electrically without introducing other effects. One objective of the project is to transform a nonsuperconducting cuprate sample into a superconductor by adding charge carriers into it. The long-term goal is to establish electrostatic charging as an important tool in the research of metal oxides with strong el ectron-electron correlations, which is potentially of great scientific and technological significance for advanced superconducting and magnetoresistive electronic devices. ***