Electronic Properties of Transition Metal Oxides

本项目的重点是研究平面内和平面外的正常态电导，使用极高质量的铜氧化物超导体和层状锰氧化物单晶。我们对高相变温度下CuO(2)晶面和面外电荷输运的物理认识还远远不够。这在一定程度上是由于缺乏对这些性质随掺杂在整个化学计量比范围内的演变的全面实验研究：欠掺杂、最佳掺杂和过度掺杂。对于铜酸盐，重点将放在相图上正常态电导的转变上，这包括绝缘、欠掺杂和过掺杂状态。提出了一系列的电输运和磁化研究。将对这些数据进行分析，以获取有关电子传输和传导机制的信息。层状锰氧化物有一个REACH相图，其中包括几个相变。这些热力学相变对电荷输运有很大的影响。通过电荷输运和磁化强度测量，将对锰氧化物的导电机制进行全面的研究。这项研究将极大地加强我们对铜酸盐和锰酸盐中电荷传导的基本理解，解决这些系统的物理中的关键问题。更广泛地说，这项基础调查的结果可能会为适当的掺杂方案提供洞察，以促进铜酸盐和锰氧化物在电子传感器和设备(如磁场传感器甚至计算机逻辑设备)中的应用。这一高度跨学科的项目有助于教育和培训博士生和本科生，以及各机构的博士后研究人员，这些机构是合作的一部分。该研究项目参与者获得的专业知识的多样性是当今以知识为基础、技术驱动的经济中的一大优势，对未来在工业、政府或学术界的职业生涯有利。本实验研究项目涉及高温超导体和层状锰氧化物的异常电学性质和行为。即使在正常状态下，高温超导体的导电方式也与库珀和硅等典型导体截然不同。此外，锰氧化物的导电性受到热力学相变的强烈影响。这个项目将极大地增强我们对铜酸盐和锰氧化物电学行为的基本理解。阐明这些新的电学行为可能有助于这些材料最终应用于电子传感器和设备，如磁场传感器，甚至计算机逻辑设备。该项目为跨学科项目中的研究生提供了极好的研究和教育机会。它涉及少数群体的研究生，他们从事论文研究，并接受对未来在工业、政府或学术界的职业有益的优秀培训。与罗马尼亚和西班牙科学家的国际合作，需要实施该项目的部分内容，为该国的研究和教育基础设施做出贡献。

This project is focused on the investigation of in-plane and out-of-plane normal-state electrical conduction, using extremely high quality single crystals of selected copper-oxide superconductors and layered manganites. Our understanding of the physics of the normal-state charge transport along the CuO(2) planes and in the out-of-plane direction in the high transition temperature Tc cuprates is still far from complete. This is in part due to the scarcity of comprehensive experimental studies on the evolution of these properties with doping across the full range of stoichiometry: under-doped, optimally-, and over-doped regimes. For the cuprates, the emphasis will be on the transformation of the normal-state conduction across the phase diagram, which includes insulating, under-doped, and over-doped regimes. A series of electrical transport and magnetization investigations are proposed. The data will be analyzed for information about electronic transport and conduction mechanisms. Layered manganites have a reach phase diagram, which includes several phase transitions. These thermodynamic phase transitions have a strong effect on the charge transport. A comprehensive study of the conduction mechanism in manganites will be undertaken through charge transport and magnetization measurements. This research will significantly enhance our fundamental understanding of charge conduction in cuprates and manganites by addressing key issues in the physics of these systems. More broadly, the results from this basic investigation may provide insight into appropriate doping schemes to facilitate applications of cuprates and manganites for electronic sensors and devices such as magnetic field sensors or even computer logic devices. This highly interdisciplinary project contributes to the education and training of doctoral and undergraduate students, as well as postdoctoral researchers at the institutions, which are part of the collaboration. The diversity of the expertise gained by the participants in this research program is a substantial advantage in today's knowledge based, technology driven economy, being beneficial to a future career in industry, government, or academia. This experimental research project concerns the unusual electrical properties and behavior of high temperature superconductors and layer manganites. The high temperature superconductors, even in the normal state, conduct electricity in ways that are very different from typical conductors such as cooper and silicon. Also, the conduction of electricity in manganites is strongly affected by thermodynamic phase transitions. This project will significantly enhance our fundamental understanding of the electrical behaviors of cuprates and manganites. Clarifying these novel electrical behaviors may contribute to eventual applications of these materials for electronic sensors and devices such as magnetic field sensors or even computer logic devices. This project offer excellent research and education opportunities for graduate students within an interdisciplinary program. It involves minority-group graduate students who pursue thesis research and receive excellent training beneficial to a future career in industry, government, or academia. The international collaborations with scientists from Romania and Spain, needed to carry out parts of this project, contribute to the nation's infrastructure for research and education.