层状三角晶格RExRhO2（RE=K, Na）晶体生长、RE精确调控及其与晶体拓扑量子特性关系的研究

项目名称： 层状三角晶格RExRhO2（RE=K, Na）晶体生长、RE精确调控及其与晶体拓扑量子特性关系的研究

项目编号： No.91622122

项目类型： 重大研究计划

立项/批准年度： 2017

项目学科： 一般工业技术

项目作者： 姚淑华

作者单位： 南京大学

项目金额： 80万元

中文摘要： 层状结构的过渡族金属氧化物RExRhO2（RE=K，Na）由于其准二维三角结构(三角晶格，层状)和4d过渡金属原子的电子关联、自旋轨道耦合作用，展现出丰富的物理效应。量子力学第一性原理预言在该体系几个特殊组分的晶体中具有一系列新颖的拓扑量子物性，比如K0.5RhO2中的量子化的反常霍尔效应，NaRhO2表面上的手性二维电子气体，K7/8RhO2中的显著热电效应。但是目前由于仍不能制备出精确控制Na或K含量并且成分均匀的单晶样品，这些预言在实验上还没有看到。本项目拟结合电化学方法制备RE含量精确控制的多晶原料和晶体退火/氟化等过程微调组分制备上述三个特殊组分的RExRhO2单晶样品。最终研究这些特殊组分的晶体的显著的(甚至量子化)的反常霍尔效应，自旋手性的表面态和显著的热电效应。本项目的实施将发展层状晶体组分精确可控、成分分布均匀的一套生长方法、研究特殊组分下的RExRhO2单晶材料

中文关键词： 晶体生长；组分调控；电输运；量子反常霍尔效应；热电效应

英文摘要： Layered transition metal oxides RExRHO2（RE=K，Na）have rich physical properties because of the layered triangular crystal structure, the electron-electron correlation in 4d-transition metal, as well as spin-orbit coupling. The first-principles calculations predict that there are a series of novel topological quantum effects, for example the quantum anomalous Hall effect in K0.5RhO2, the two-dimensional chiral electron gas on the surface of NaRhO2, and significant thermoelectric effect in KK7/8RhO2 andNa0.83RhO2. But experimental observation these predictions are hindered by the difficulty of precisely controlling RE concentration in these crystal. This project plans to grow the special RE concentration RExRhO2 crystals by combining electrochemical method controlling RE concentration in raw powders, forecile growth of optical flating zone, as well as later annealing/fluoridizing to refine the RE concentration And finally study the significant (even quantum) anomalous Hall effect in K0.5RhO2, chiral two-dimensional electron gas on the surface of NaRhO2, and significant thermoelectric effect in K7/8RhO2. This project will develop a systematic method to synthesize the layered compounds with special concentrations, and characterize the quantum physical properties in these compounds, which will deepen our understanding of topological quantum properties in the systems with both electron-electron correlation and spin-orbit coupling.

英文关键词： crystal growth; concentration controlling ;electrial transport;quantum anomalous hall effect ;thermoelectric