5d过渡金属铱氧化物高压物性研究

In 5d transition metal iridium oxides, strong competition and cooperation between spin-orbit coupling and on-site Coulomb interaction drive rich physics. In this project, we will focus on some of intriguing phenomena, such as iridates tending to insulator at high pressures and displaying abnormal magneto-resistance under magnetic field. The Ruddlesden-Popper iridates Sr2IrO4 and Sr3Ir2O7 will be investigated by combining high pressure and high magnetic field, especially via electrical transport, Raman, and synchrotron x-ray diffraction experiments under ultrahigh pressure above 100 GPa. Through this project, we will try to understand why iridates seldom metalize at high pressures, therefore construct the correlation between physical properties and structure. These experiments will also allow us to map out the field-pressure-temperature phase diagram for these materials. On the basis of realizing the metallization, exotic quantum states such as superconductivity will be explored. The implement of the project will be beneficial for understanding the interaction between spin-orbit coupling and on-site Coulomb repulsion.

在5d过渡金属铱氧化物中，自旋-轨道耦合与电子间关联作用的协同与竞争导致了丰富的物理内容，本项目将针对5d过渡金属铱氧化物高压下趋向绝缘、磁场下磁电阻反常等科学问题，选取不同元素掺杂的Ruddlesden-Popper型Sr2IrO4和Sr3Ir2O7为研究对象，通过外加压力与磁场相结合，特别是通过超高压（100 GPa之上）下电输运、X射线衍射、拉曼光谱等实验测量，研究铱氧化物高压下难以金属化的原因，建立材料宏观物性与晶体结构或微结构之间的关联，构筑完善的温度-压力-磁场相图，并在实现金属化的前提下探索可能的非常规超导电性等新奇物态。本项目的顺利完成将有助于深入理解强自旋-轨道耦合与电子关联的协同作用机理。

在5d过渡金属化合物中，自旋-轨道耦合与电子间关联作用的协同与竞争导致了丰富的物理内容，本项目选取自旋轨道耦合与电子关联协同作用体系如Sr2IrO4、La3Ir3O11等为研究对象，通过压力、磁场调节不同相互作用的竞争，主要研究成果如下：1. 揭示了5d过渡金属铱氧化物Sr2IrO4为百万大气压下的永久绝缘体；2. 发现了一种具有新颖结构的准一维5d过渡金属超导体；3. 在非常规超导电性探索方面，实验发现了压力诱导CsV3Sb5超导电性的再入现象，并在10种材料中发现压力诱导的超导电性；4. 在磁性拓扑材料的研究中，揭示了压力诱导的拓扑相变和磁相变，构筑了完善的温度-磁场-压力相图。在本项目资助下，项目负责人以通讯作者共发表SCI论文26篇，其中Adv. Mater. 1篇、NPG Asia Materials 1篇、Materials Today Physics 1篇、Sci. China-Phys. Mech. Astron. 1篇、Phys. Rev. B/ Mater. 14篇、Appl. Phys. Lett. 2篇、Adv. Electron. Mater. 2篇。