锇体系新超导材料探索

Our main focus of this project is to search for new superconducting materials on 5d Osmium (Os) oxides: the exploration of novel and high quality Osmium oxide superconducting compounds; the investigation structure and superconducting properties of these superconductors. .The sample preparation is the most important for researching new osmium oxide materials in this program. The efforts by applying the atmosphere pressure, high pressure, and high temperature solid state chemical way could be used to search for new materials on osmium oxide system. Also, assisted by other common ways, such as doping, oxidation-reduction reaction, intercalation reaction, and soft-chemical way, some novel superconducting materials can be expected in this sample series. .For structural and superconducting properties characterizations, high sensitive SPring-8, X-ray diffractometer, TEM, Quantum Design MPMS-XL Squid, PPMS, and so on, will serve as an excellent platform.SPring-8 will be used to analyze the crystal structures of the sample. Combined with the TEM and analysis software bundles, we can obtain the detailed structure analysis for the superconducting materials, and find the relationship between the structure and the superconductivity. We will characterize the physical properties for new materials by using MPMS and PPMS, including resistivity, magnetic properties, specific heat, thermo-power, thermal conductivity, Hall coefficient, and so on. In addition, the first-principle calculations on the electronic structures can be used to analyze the physics and verify the experimental data..The 3d and 4d metal oxides have been intensively studied to search for new materials, whereas the 5d Os oxide series are not. However, the previous results for osmium oxides studies also display ravel complex and multivariate physical phenomena in this system, such as superconductivity, magnetic ordering, metal-insulator transition behaviors, etc., which usually occurred in 3d or 4d metal transition oxides. These observed novel and unconventional physical properties, especially the superconductivity, are the frontier in condensed matter physics. This project is valuable for fundamental research due to the new superconductors, new phenomena and novel physical properties. These rich properties may generate new insights on the superconducting mechanism, and help us well understand the 5d metal transitional oxides materials.

本项目以探索5d电子过渡金属氧化物锇（Os）体系新超导材料为研究对象，采用高压或常压合成材料方法，制备系列该体系新材料，或通过掺杂、氧化还原、插层等化学方法，从中希望能够发现新的超导材料，并各种仪器和检测方法，研究其结构和超导电性以及结构和超导之间的关联。在已进行的金属氧化物锇（Os）体系的研究发现，与3d 和4d电子过渡金属氧化物一样，它们具有复杂和多变的物理行为，包括超导电性、磁有序、金属－绝缘体转变等复杂行为，而这些性质，特别是新超导材料的研究，目前是凝聚态物理领域的一个研究热点。针对具有奇异物性的锇体系新材料，如新超导体系或关联体系中可能出现的相变、有序态之间的竞争、演生现象等深层次丰富物性，使得能够更好的理解5d 过渡金属氧化物。我们希望通过锇体系超导材料的探索，发现新材料、新现象和物性，揭示其背后物理机理。

超导材料的探索是凝聚态物理的重要研究领域，包含大量前沿研究课题。目前, 物理学界对高温超导机制仍未形成一致看法, 研究人员希望在铜氧化物和铁基超导材料以外再找到新的高温超导材料, 以期从新的途径来破译高温超导机理。.本项目以探索5d 电子过渡金属氧化物锇（Os）体系新超导材料为研究对象，希望能够发现新的超导材料，并研究其结构和超导电性以及结构和超导之间的关联。在已进行的金属氧化物锇（Os）体系的研究发现，与3d 和4d电子过渡金属氧化物一样，它们具有复杂和多变的物理行为，包括超导电性、磁有序、金属－绝缘体转变等复杂行为，而这些性质，特别是新超导材料的研究，目前是凝聚态物理领域的一个研究热点。针对具有奇异物性的锇体系新材料，如新超导体系或关联体系中可能出现的相变、有序态之间的竞争、演生现象等深层次丰富物性，使得能够更好的理解5d 过渡金属氧化物。.我们在5d锇体系中进行了大量的新材料探索，（1）发现了YbOs2Al10、LuOs2Al10等新材料，并生长了高质量单晶，详细研究了其结构和YbOs2Al10中4f电子对其磁性和输运性质的影响；（2）制备了准方钴矿结构Yb3Os4Ge13新材料并生长了高质量单晶，研究了Yb3Os4Ge13的近藤效应，并分析了其近藤效应和4f电子的关联。其他体系方面（3） 生长了高质量Na2Ti2As2O单晶，并研究了磁性和输运性质方面的各向异性，研究了其电荷密度波（CDW）性质。（4）生长了高质量WTe2单晶，研究了其庞磁阻物性，为其他课题组的物性检测提供了研究所素材。（5）生长了高质量TaAs2单晶材料，研究了其结构和庞磁阻物性。.5d锇体系新材料探索为我们了解锇电子体系提供了素材。功能材料单晶生长为验证理论预言和物性测试需求提供了高质量单晶样品。