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. ***
