Transport and Magnetic Studies of Phase Separation and Electron Correlations in Magnetic and Superconducting Oxides

这个个人研究奖是给迈阿密大学的一位年轻教授的，他的实验研究项目集中在电荷载流子掺杂的反铁磁（AF）锰氧化物和铜氧化物中的电子相分离现象。电子掺杂的锰氧化物，例如Ca（1-x）La（x）MnO（3）（x = 0.2），已经通过初步数据显示为用于测试相分离的理论预测的模型系统，并且是进一步研究的目标。对铜酸盐的研究是基于一个假设，即AF YBa（2）Cu（3）O（6+x）中的反常声子阻尼归因于相分离的CuO（2）平面中的电荷条纹动力学引起的局域晶格畸变。特别感兴趣的拟议工作是绝缘体-超导体相边界（x~0.3-0.4）附近的成分，在那里的电荷条纹秩序的发展与长程尼尔秩序竞争。 对层状超导体Sr（2）RuO（4）的平行研究将补充这些对非均匀材料的研究。实验提出测试费米液体理论的适用性的限制，这个高度相关的，各向异性的系统。 预计这项工作将大大提高对自旋，电荷和晶格激发之间相互作用的理解，这些相互作用决定了过渡金属氧化物的新物理性质。参与该项目的年轻科学家，从本科生到博士后，将接受培训，使他们能够在学术界，政府或工业实验室竞争未来的职位。%此个人研究者奖授予迈阿密大学的一位年轻教授，以表彰他的一项实验研究项目，该项目专注于过渡金属氧化物化合物中的传输（电和热传导，热电效应）和磁性的研究，具有重大的智力和技术意义。三类化合物（锰氧化物、铜酸盐和三氧化二锰），表现出磁性和/或非常规超导性，已成为研究的目标。锰氧化物和铜酸盐是其中物理性质可以通过经由化学取代添加电荷载体（掺杂）而可控地改变的系统。该计划的一个重要主题是电子相分离（PS）现象，其中掺杂到绝缘反铁磁化合物中的电荷分离成纳米级簇。这种小尺度的不均匀性似乎是这些材料所固有的，并且可能对技术发展具有重要意义，因为最近的实验和理论表明PS是巨磁阻和高温超导机制中的重要成分。参与该项目的年轻科学家，从本科生到博士后，将接受培训，使他们能够在学术界，政府或工业实验室竞争未来的职位。

This individual investigator award is to a young professor at the University of Miami for an experimental research project that focuses on the phenomenon of electronic phase separation in charge-carrier-doped antiferromagnetic (AF) manganites and cuprates. Electron-doped manganites, for example Ca(1-x)La(x)MnO(3) (x = 0.2), have been shown through preliminary data to be model systems for testing theoretical predictions of phase separation and are targeted for further study. The research on cuprates is motivated by a hypothesis that attributes anomalous phonon damping in AF YBa(2)Cu(3)O(6+x) to local lattice distortions induced by charge-stripe dynamics in the phase-separated CuO(2) planes. Of particular interest for the proposed work are compositions near the insulator-superconductor phase boundary (x~0.3-0.4), where the development of charge-stripe order competes with long-range Neel order. Complementing these investigations of inhomogeneous materials will be parallel studies of the layered superconductor Sr(2)RuO(4). Experiments are proposed to test the limits of applicability of Fermi-Liquid theory to this highly correlated, anisotropic system. The proposed work is expected to significantly enhance the understanding of the interplay between spin, charge, and lattice excitations that determine the novel physical properties of transition-metal oxides. The young scientists involved with this project, undergraduate students through postdocs, will receive training that will enable them to compete for future positions in academia, government, or industrial laboratories. %%%This individual investigator award is to a young professor at the University of Miami for an experimental research project that focused on the investigation of transport (electrical and heat conduction, thermoelectric effects) and magnetism in transition-metal oxide compounds that are of significant intellectual and technological interest. Three classes of compounds (manganites, cuprates, and ruthenates), that exhibit magnetism and/or unconventional superconductivity, have been targeted for study. The manganites and cuprates are systems where the physical properties can be controllably altered by adding charge carriers (doping) via chemical substitution. An important theme for this program is the phenomenon of electronic phase separation (PS), wherein the charges doped into insulating antiferromagnetic compounds segregate into nano-scale clusters. This small-scale inhomogeneity appears to be intrinsic to these materials and may prove significant for technological development, given that recent experiments and theory suggest PS is an important ingredient in the mechanisms for colossal magnetoresistance and high-temperature superconductivity. The young scientists involved with this project, undergraduate students through postdocs, will receive training that will enable them to compete for future positions in academia, government, or industrial laboratories.***