Electronic Properties of Transition Metal Oxides

Kent State University, Kent OH

Investigators

Abstract

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.