Continuous Metal-Insulator Transitions in Highly Correlated Systems

9801824 Rosenbaum在这项由Th. A.芝加哥大学詹姆斯弗兰克研究所的罗森鲍姆提出了金属-绝缘体问题 (MI)过渡导致的 不断变化 在 外部 参数 将 被 实验研究。 具体地说， 的 连续 研究了NiS（2-x）Sex中的Mott-Hubbard跃迁、金属氢化物薄膜中的MI跃迁和三氧化二钒在高度无序极限下的MI跃迁。 这些研究对新材料的性质有重要的影响，如过渡金属氧化物和硫化物，高Tc超导铜酸盐，巨磁电阻锰酸盐，以及其他受强载流子关联控制的材料。 本研究的目的是阐明MI转变的基本性质的材料中，电子-电子相互作用占主导地位，并在那里可以应用从连续相变的研究中获得的经验。 当前技术上重要的许多材料，例如过渡金属氧化物和硫化物、金属硫化物、高温氧化物和金属氧化物。 超导 铜酸盐， 巨磁阻锰氧化物表现出尚未完全理解的行为。 这种缺乏详细了解的情况阻碍了它们在技术设备中的有效应用。 在这些性质中，材料在系统中从金属到绝缘体（MI）的连续变化是电荷载流子的行为高度相关的。 例如，在液氦温度下，材料的电导率可以变化32个数量级。 直到去年才发现材料系统（掺杂半导体和非晶合金）中MI转变以连续的方式响应于外部参数的变化而进行。 本研究的目的是阐明 材料中MI转变的基本性质，其中电子-电子相互作用占主导地位，并且可以应用从连续相变获得的经验。 这些研究结果对新型和改进型电子固体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. ***