Magnetism and Superconductivity in Ruthenate-Cuprates: New Pathways to Novel Materials

[0105398] Dabrowski该项目的一个重要推力将解决复杂氧化物陶瓷材料合成的重要问题，并将提供高质量的研究材料，包括新化合物的单晶。这些复杂的过渡金属氧化物表现出强烈的电子-电子、电子-磁振子和电子-声子相互作用。由于这些强相互作用，这些系统中的传导电子不能单独考虑，集体行为最好用高度相关的电子系统来描述。在此背景下，我们将广泛研究红宝石酸盐的超导性和磁性，以及含有Ru和0离子八面体排列的非超导复合氧化物的选定相的磁性。提出的研究还将解决钌酸盐中超导性和弱铁磁性共存的问题，这在高温超导体家族中仍然是独一无二的，因为磁性顺序起源于d电子钌离子的亚晶格。研究工作的学生将被引导完成复杂的制造过程（包括我们独特的高压氧合成能力，导致我们最近发现了新的Ru1-xSr2GdCu2+xO8-d超导和磁性相）和材料表征。参与的学生将通过参与在阿贡国家实验室利用基于x射线同步加速器（先进光子源）和中子衍射技术的实验，接触到尖端技术的使用。补充的μ子自旋旋转实验将提供对局部磁结构的独特见解，并将由与瑞士保罗谢勒研究所的研究团队建立的合作促进。推进复杂过渡金属氧化物陶瓷的基本理解和相关应用受到当前我们对这些系统中存在的复杂相互作用的知识的限制。这些化合物的研究构成了现代固态陶瓷及其相关物理和化学的前沿。通过对一类最近发现的磁性高温超导体的研究，该项目将大大提高我们对磁性和超导性共存的长期问题的理解。我们独特的合成途径已经导致发现新的超导相的红宝石酸盐和显着的改变磁性复杂的红宝石酸盐。除了研究这些材料的性质外，本课程的重点将放在研究合成-结构-性质的关系，并利用我们独特的高压氧合成能力探索新化合物的加工路线。在现有合作努力的框架内，还计划与来自瑞士Paul Sherrer研究所和波兰科学院的研究小组进行补充实验。该项目将为学生提供宝贵的当代经验、培训和技能，使他们能够在我们的实验室和阿贡国家实验室的实验设施中使用最先进的仪器（先进光子源的尖端x射线同步辐射技术和强脉冲中子源的中子衍射实验）。

0105398 Dabrowski A significant thrust of this project will address issues important to the materials synthesis of complex oxides ceramics and will provide superior quality research material including single crystals of novel compounds. These complex transition metal oxides exhibit strong electron-electron, electron-magnon, and electron-phonon interactions. Because of these strong interactions, conduction electrons in these systems cannot be considered separately and the collective behavior is best described in terms of highly correlated electron systems. In this context an extensive study will be made of the superconducting and magnetic properties of ruthenocuprates and magnetic properties of selected phases of non- superconducting complex oxides that contain the octahedral arrangement of Ru and 0 ions. The proposed research will also address the problem of coexistence of superconductivity and weak- ferromagnetism in ruthenocuprates, which remains unique in the family of high-temperature superconductors, since the magnetic order originates in the sublattice of d-electron Ru ions. Students in the research work will be guided through the complex process of fabrication (including our unique high- pressure oxygen synthesis capabilities that lead us recently to discovery of novel Ru1-xSr2GdCu2+xO8-d superconducting and magnetic phases) and materials characterization. Participating students will be exposed to the use of cutting-edge techniques through their involvement in experiments utilizing the X-ray synchrotron based (Advanced Photon Source) and neutron diffraction techniques at Argonne National Laboratory. Supplementary muon spin rotation experiments that provide unique insights into local magnetic structure are planned and will be facilitated by the established cooperation with research team at the Paul Sherrer lnstitut in Switzerland. Advancing the fundamental understanding and associated applications of complex transition metal oxide ceramics is constrained by the current limits of our knowledge of the complex interactions present in these systems. Study of these compounds constitutes the frontier of modern solid-state ceramics and its associated physics and chemistry. The proposed project will substantially enhance our understanding of the long-standing issue of the coexistence of magnetism and superconductivity by studies of a class of recently discovered magnetic high temperature superconductors. Our unique pathways to synthesis have led to discovery of new superconducting phases of ruthenocuprates and to significant modification of magnetic properties of complex ruthenates. Beyond investigating the properties of these materials, emphasis will be placed on studying the synthesis-structure-properties relationships and exploring processing routes for novel compounds in this class using our distinctive high-pressure oxygen synthesis capabilities. Supplementary experiments are also planned, within the frame of existing cooperative efforts, with research teams from the Paul Sherrer Institut in Switzerland and the Polish Academy of Sciences in Poland. The inclusion of students in this project will provide them with valuable, contemporary experience, training, and skill with state-of-the art instrumentation in our laboratory and in the experimental facilities of Argonne National Laboratory (cutting-edge X-ray synchrotron radiation based techniques at the Advanced Photon Source and neutron diffraction experiments at the Intense Pulsed Neutron Source).