4d and 5d Transition Metal Oxides: A New Frontier of Materials with Exotic Phenomena

这个个人研究奖支持系统的努力，以阐明4d和5d过渡金属氧化物的基本物理。这些系统是一类新的材料，其特征在于不同自由度之间的强耦合和不同种类的有序共存。最近的发现显示了一些有趣的物理性质的4d电子基的三烯酸盐（Sr，Ca）（n +1）Ru（n）O（3n +1）和5d电子基的铱酸盐Sr（n +1）Ir（n）O（3n +1），并提供了强有力的动机进行深入的研究。这些层状材料表现出惊人的物理性质的维度依赖性和广泛的奇异现象，包括费米子-准粒子和非金属特性的共存，面间隧穿磁阻，巨磁阻（CMR），CMR和磁化的显著不同的各向异性，p波超导性，变磁性，绝缘状态下的"抗磁性"等。这些现象反映了新的物理，而正是这种新的物理学需要被彻底研究。计划中的方案包括单晶生长（通量和浮区法）和这些材料的热，电，磁和结构特性的实验研究，作为温度，化学掺杂，磁场和压力的函数。参与研究的研究生将接受严格的培训，重点是材料开发、合成和表征。在我们的研究生教育中，这种类型的培训现在特别需要，因为缺乏专门开发新材料和生长单晶的科学家已经阻碍了美国凝聚态物理学的进步。这个个人研究者奖支持一个系统的努力，以阐明4d和5d过渡金属氧化物的基本物理，这是一个未知的领域，丰富的新的物理现象，不能通过我们的传统理解解释。 最近的发现显示了4d-电子基的单烯酸盐和5d-电子基的铱酸盐的有趣的物理性质的一瞥，并提供了强大的动机进行彻底的研究。这些层状材料表现出惊人的尺寸依赖性的物理特性和各种奇异的现象，包括新的超导性和共存的不同种类的有序，这是传统上预计将相互排斥等这些现象在很大程度上违背了传统的智慧，并反映了新的物理学，这是需要彻底研究的新物理。计划中的项目包括材料合成和这类材料的热、电、磁和结构特性的实验研究，这些特性是温度、化学取代、磁场和压力的函数。参与研究的研究生将接受严格的培训，重点是材料开发，合成和表征。在我们的研究生教育中，这种类型的培训现在特别需要，因为缺乏专门开发新材料和生长单晶的科学家已经阻碍了美国凝聚态物理学的进步。

This individual investigator award supports a systematic effort to elucidate underlying physics of the 4d and 5d transition metal oxides. These systems are a new class of materials characterized by strong coupling between different degrees of freedom and the coexistence of different kinds of ordering. Recent discoveries show a glimpse of intriguing physical properties of 4d-electron based ruthenates (Sr,Ca)(n+1)Ru(n)O(3n+1) and 5d-electron based iridates Sr(n+1)Ir(n)O(3n+1), and provide strong motivation for a thorough investigation. These layered materials exhibit an astonishing dimensionality-dependence of physical properties and a wide array of exotic phenomena including coexistence of fermion-quasiparticle and nonmetallic characteristics, inter-plane tunneling magnetoresistance, colossal magnetoresistance (CMR), drastically different anisotropies of the CMR and magnetization, p-wave superconductivity, metamagnetism, "diamagnetism" in an insulating state, etc. These phenomena reflect new physics, and it is this new physics that needs to be thoroughly studied. The planned program includes single crystal growth (both flux and floating zone methods) and experimental studies of thermal, electronic, magnetic and structural properties of these materials as a function of temperature, chemical doping, magnetic field and pressure. Graduate students involved in the research will receive rigorous training with an emphasis on materials developments, synthesis, and characterizations. This type of training in our graduate education is particularly needed nowadays as the lack of scientists who specialize in both developing new materials and growing single crystals has already hindered advancements in condensed matter physics in the US. This individual investigator award supports a systematic effort to elucidate underlying physics of the 4d and 5d transition metal oxides, which are by and large an uncharted territory rich with novel physical phenomena that cannot be explained through our conventional understanding. Recent discoveries show a glimpse of intriguing physical properties of 4d-electron based ruthenates and 5d-electron based iridates, and provide strong motivation for a thorough investigation. These layered materials exhibit an astonishing dimensionality-dependence of physical properties and a wide array of exotic phenomena including novel superconductivity and the coexistence of different kinds of ordering, which are conventionally expected to exclude each other, etc. These phenomena largely defy conventional wisdom and reflect new physics, and it is this new physics that needs to be thoroughly studied. The planned program includes materials synthesis and experimental studies of thermal, electronic, magnetic and structural properties of this class of materials as a function of temperature, chemical substitution, magnetic field and pressure. Graduate students involved in the research will receive rigorous training with an emphasis on materials developments, synthesis, and characterizations. This type of training in our graduate education is particularly needed nowadays as the lack of scientists who specialize in both developing new materials and growing single crystals has already hindered advancements in condensed matter physics in the United States.