Novel States in Spin-Orbit-Coupled and Correlated Materials

摘要：现代凝聚态物理研究已经产生了具有基本性质的新型材料，这些材料支撑着许多尖端技术。现在人们普遍认为，新材料对于技术的关键进步是必要的，谁发现了新材料，谁就控制了未来的科学和技术。过渡金属氧化物在基础科学界和应用科学界都引起了极大的兴趣。然而，几十年来，绝大多数的努力都集中在3d元素（如铁、铜等）及其化合物上；较重的4d和5d元素（如钌、铱等，它们构成了元素周期表中所列d元素的三分之二）及其化合物直到最近才在很大程度上被忽视。首席研究员寻求发现含有4d和/或5d元素的新材料，并了解它们如何为发现新物理以及最终的新设备范例提供广泛的机会。该项目还为所有参与的学生提供严格的培训，重点是合成和表征技术，涵盖广泛的材料和主要研究者实验室中可用的实验探针。技术摘要：自旋轨道相互作用驱动的物理学是当代凝聚态物理学中最重要的课题之一。由于自旋轨道相互作用可与现场库仑和其他相关相互作用相媲美，因此它在驱动复杂行为的竞争相互作用和在其他材料中未观察到的奇异状态之间创造了独特的平衡。该项目包括系统地阐明自旋轨道耦合和相关材料中新现象的物理学，以及对具有奇异基态的新材料的严格搜索。本项目重点研究以下几个方面：(1)高压、高磁场下的新现象；(2)铱酸盐和钌酸盐中绝缘间隙与磁跃迁之间的异常相关性；(3)铱酸盐中的奇异金属态和超导态；(4)具有“中等强度”自旋轨道相互作用和其他竞争能量的莫特绝缘体；(5)单晶合成和新材料的寻找。首席研究员是少数几个主要的先驱之一，他发起了对铱酸盐和之前的钌酸盐的开创性研究，并拥有全面的设施和成熟的单晶合成专业知识，并广泛研究了结构，输运，磁性，热和介电性质作为温度，磁场，压力和掺杂的功能。

Non-technical Abstract:Modern condensed matter physics research has produced novel materials with fundamental properties that underpin a remarkable number of cutting-edge technologies. It is now generally accepted that novel materials are necessary for critical advances in technologies and whoever discovers novel materials generally controls the science and technology of the future. Transition metal oxides have attracted enormous interest within both the basic and applied science communities. However, for many decades, the overwhelming balance of effort was focused on the 3d-elements (such as iron, copper, etc.) and their compounds; the heavier 4d- and 5d-elements (such as ruthenium, iridium, etc., which constitute two thirds of the d-elements listed in the Periodic Table) and their compounds have been largely ignored until recently. The principal investigator seeks to discover novel materials containing 4d- and/or 5d-elements and understand how they offer wide-ranging opportunities for the discovery of new physics and, ultimately, new device paradigms. This project also provides rigorous training to all students involved, focusing on synthesis and characterization techniques covering a broad spectrum of materials and experimental probes available in the principal investigator's laboratory. Technical Abstract:Physics driven by spin-orbit interactions is among the most important topics in contemporary condensed matter physics. Since the spin-orbit interaction is comparable to the on-site Coulomb and other relevant interactions, it creates a unique balance between competing interactions that drive complex behaviors and exotic states not observed in other materials. The project encompasses a systematic effort to elucidate physics of novel phenomena in spin-orbit-coupled and correlated materials and a rigorous search for new materials having exotic ground states. This project focuses on the following areas: (1) Novel phenomena at high pressures and high magnetic fields, (2) Unusual correlations between the insulating gap and magnetic transition in iridates and ruthenates, (3) Exotic metallic and superconducting states in iridates, (4) Mott insulators with "intermediate-strength" spin-orbit interaction and other competing energies, and (5) Single-crystal synthesis and search for novel materials. The principal investigator is one of a few key pioneers who have initiated seminal studies on iridates and, before that, ruthenates, and has comprehensive facilities and proven expertise for single-crystal synthesis and wide-ranging studies of structural, transport, magnetic, thermal and dielectric properties as functions of temperature, magnetic field, pressure and doping.