Continuous Metal-Insulator Transitions in Highly Correlated Systems

9801824 Rosenbaum教授进行的这项研究。芝加哥大学詹姆斯·弗兰克研究所的a·罗森鲍姆（A. Rosenbaum）将对外部参数连续变化引起的金属-绝缘体（MI）跃迁问题进行实验研究。具体来说，将研究NiS（2-x）性的连续Mott-Hubbard跃迁，金属氢化物薄膜中的MI跃迁，以及半氧化钒在高度无序极限下的MI跃迁。这些研究对过渡金属氧化物和硫化物、高tc超导铜酸盐、巨磁阻锰酸盐等由强载流子相关性控制的新材料的性质具有重要意义。本研究的目的是阐明在电子-电子相互作用占主导地位的材料中MI转变的基本性质，以及有可能应用从连续相变研究中获得的经验。许多目前技术上重要的材料，如过渡金属氧化物和硫化物、金属氢化物、高温超导铜酸盐、巨磁阻锰酸盐，表现出的行为尚未完全被理解。%%% %缺乏详细的了解阻碍了它们在技术设备中的有效应用。在这些性质中，在电荷载流子的行为高度相关的系统中，材料从金属到绝缘体（MI）的连续变化。例如，在液氦温度下，材料的电导率可以变化32个数量级。直到去年，人们才发现了一些材料系统（掺杂半导体和非晶合金），在这些系统中，随着外部参数的变化，MI跃迁以连续的方式进行。本研究的目的是阐明在电子-电子相互作用占主导地位的材料中MI转变的基本性质，以及有可能应用从连续相变中获得的经验。这些研究结果将对新型和改进的电子固态材料的开发和应用具有重要意义。＊＊＊

9801824 Rosenbaum In this research conducted by Prof. Th. A. Rosenbaum of the James Franck Institute of the University of Chicago the problem of metal-insulator (MI) transitions resulting from continuous changes in external parameters will be experimentally investigated. Specifically, the continuous Mott-Hubbard transition in NiS(2-x)Sex, the MI transition in metal hydride films, and the MI transition in vanadium sesquioxide in the highly disordered limit will be studied. These researches have important bearing on the properties of novel materials, such as transition metal oxides and sulfides, high-Tc superconducting cuprates, giant magnetoresistance manganates, and others that are governed by strong charge carrier correlations. The purpose of this research is to elucidate the fundamental nature of the MI transition in materials where electron-electron interactions dominate and where it is possible to apply the experience obtained from studies of continuous phase transitions. %%% Many materials of current technological importance, such as, for example, transition metal oxides and sulfides, metal hydrides, high-temperature superconducting cuprates, colossal magnetoresistance manganates, exhibit behaviors that are not yet fully understood. This absence of detailed understanding impedes their efficient application in technological devices. Among these properties is the continuous change of a material from a metal to an insulator (MI) in systems in which the behavior of the electric charge carriers is highly correlated. For example, at liquid helium temperatures the electrical conductivities of materials can vary by 32 orders of magnitude. It was only during the last year that materials systems were discovered (doped semiconductors and amorphous alloys) in which the MI transition proceeds in a continuous manner in response to the variations of an external parameter. The purpose of this research is to elucidate the fundamental nature of the MI transition in materials where electron-electron interactions dominate and where it is possible to apply the experience obtained from continuous phase transitions. The results of these investigations will be of great importance for the development and application of new and improved electronic solid state materials. ***