Emergent Quantum Phenomena in Layered Ruthenates and Iron Chalcogenides

****技术摘要****相关电子材料中的新兴量子现象不仅在能源和信息技术的先进应用中显示出前景，而且对凝聚态物理的现有知识提出了挑战。本项目将重点研究两种相关的材料体系，即层状钌酸盐和硫属铁。由于电荷、自旋、晶格和轨道自由度之间复杂的相互作用，这两种材料系统都为观察新的量子现象提供了绝佳的机会。对于钌酸盐，该项目旨在寻找与量子格里菲斯现象相关的新量子相，并阐明各种不寻常磁相变的机制。对于硫属铁，目标是寻求突发性磁现象和非常规超导性。该项目将汇集广泛的专业知识，包括晶体生长，特性表征，中子散射和光谱学，以全面了解相关电子的新兴量子现象。该项目将通过以下努力与教育活动相结合：a)让研究生和本科生参与研究；b)为工程物理专业的学生开发高级设计项目；c)指导当地高中的学生进行独立研究项目。****非技术摘要****具有强电子-电子相关性的材料通常被认为是开发下一代电子产品的关键。该项目的目的是寻找新的量子现象，并研究它们在两种相关材料体系中的潜在物理现象，即层状钌酸盐和硫属铁。这两种材料系统都显示出各种令人兴奋的特性，如金属-绝缘体跃迁和非常规形式的超导性和磁有序。这些材料的一个显著特点是它们的性能对外部刺激敏感，并且它们的性能可以通过磁场、压力和化学替代来调节；这为研究与相关电子复杂相变相关的新物理提供了极好的机会。该项目将汇集广泛的专业知识，以全面理解相关电子的新兴量子现象。该项目将通过以下努力与教育活动相结合：a)让研究生和本科生参与研究；b)为工程物理专业的学生开发高级设计项目；c)指导当地高中的学生进行独立研究项目。

****Technical Abstract****Emergent quantum phenomena in correlated electron materials not only show promise for use in advanced applications in energy and information technologies, but also challenge current knowledge in condensed matter physics. This project will focus on two correlated material systems, i.e. layered ruthenates and iron chalcogenides. Both material systems provide remarkable opportunities for observing novel quantum phenomena due to complex interplay between the charge, spin, lattice and orbital degrees of freedom. For ruthenates, the project aims at searching for a novel quantum phase related to the quantum Griffiths phenomena and elucidating the mechanism for various unusual magnetic phase transitions. For iron chalcogenides, the goal is to seek emergent magnetic phenomena and unconventional superconductivity. This project will bring together a wide range of expertise including crystal growth, property characterization, neutron scattering and optical spectroscopy to enable comprehensive understanding of emergent quantum phenomena of correlated electrons. This project will be integrated with education activities through the following efforts: a) involving graduate and undergraduate students in the research, b) developing senior design projects for students majoring in Engineering Physics, and c) guiding students from a local high school in an independent research project.****Non-Technical Abstract**** Materials with strong electron-electron correlation are commonly believed to hold the key for developing the next generation of electronics. The objective of this project is to search for novel quantum phenomena and investigate their underlying physics in two correlated material systems, i.e. layered ruthenates and iron chalcogenides. Both material systems have been found to show various exciting properties, such as metal-insulator transitions and unconventional forms of superconductivity and magnetic ordering. One of the remarkable characteristics of these materials is that their properties are sensitive to external stimuli and their properties can be tuned by magnetic field, pressure and chemical substitution; this provides wonderful opportunities to study the novel physics associated with complex phase transitions of correlated electrons. This project will bring together a wide range of expertise to enable comprehensive understanding of emergent quantum phenomena of correlated electrons. This project will be integrated with education activities through the following efforts: a) involving graduate and undergraduate students in the research, b) developing senior design projects for students majoring in Engineering Physics, and c) guiding students from a local high school in an independent research project.