Single-layer CrI3 grown by molecular beam epitaxy  

分子束外延生长单层CrI3

作　　者：Peigen Li Cong Wang Jihai Zhang Shenwei Chen Donghui Guo Wei Ji Dingyong Zhong 李培根;王聪;张济海;陈沈威;郭东辉;季威;钟定永(School of Physics,Sun Yat-sen University,Guangzhou 510275,China;Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-Nano Devices,Department of Physics,Renmin University of China,Beijing 100872,China;State Key Laboratory for Optoelectronic Materials and Technologies,Sun Yat-sen University,Guangzhou 510275,China)

机构地区：[1]School of Physics,Sun Yat-sen University,Guangzhou 510275,China [2]Beijing Key Laboratory of Optoelectronic Functional Materials&Micro-Nano Devices,Department of Physics,Renmin University of China,Beijing 100872,China [3]State Key Laboratory for Optoelectronic Materials and Technologies,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Science Bulletin》2020年第13期1064-1071,M0003,共9页科学通报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (11974431, 11832019, 11622437, 61674171 and 11974422);Guangzhou Science and Technology Project (201707020002);the Strategic Priority Research Program of Chinese Academy of Sciences (XDB30000000);the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China (16XNLQ01);supported by the Outstanding Innovative Talents Cultivation Funded Programs 2017 of Renmin University of China。

摘　　要：Single-and few-layer chromium triiodide(CrI3),which has been intensively investigated as a promising platform for two-dimensional magnetism,is usually prepared by the mechanical exfoliation.Here,we report direct growth of single-layer CrI3 using molecular beam epitaxy in ultrahigh vacuum.Scanning tunneling microscopy(STM),together with density functional theory(DFT)calculation,revealed that the iodine trimers,each of which consists of three I atoms surrounding a three-fold Cr honeycomb center,are the basic units of the topmost I layer.Different superstructures of single-layer CrI3 with periodicity around 2–4 nm were obtained on Au(111),while only the 1×1 structure was observed on the graphite substrate.At an elevated temperature of 423 K,single-layer CrI3 began to decompose and transformed into single-layer chromium diiodide.Our bias-dependent STM images suggest that the unoccupied and occupied states are spatial-separately distributed,consistent with the results of our DFT calculation.We also discussed the role of charge distribution in the super-exchange interactions among Cr atoms in single-layer CrI3.本文报道了在超高真空下,通过分子束外延生长单层CrI3在Au(111)和高定向石墨衬底上.基于扫描隧道显微镜和密度泛函理论计算,作者揭露了单层CrI3的表面原子结构以及其电子态的空间分布.此外,该工作还发现,在Au(111)上的单层CrI3具有不同的超结构,而在高定向石墨衬底上只有本征的CrI3.另外,一个详细的Cr-ICr的铁磁超交换机制被揭露,这将对理解强的面外铁磁性具有很大的帮助.利用分子束外延在超高真空下生长单层CrI3提供了一个新的平台研究二维磁性,这对今后的二维磁性研究提供了一个新的路线.

关 键 词：Two-dimensional magnetic materials CrI3 Molecular beam epitaxy Scanning tunneling microscopy 

分 类 号：TM271[一般工业技术—材料科学与工程]