Zhou Jiadong, Lin Junhao, Sims Hunter, Jiang Chongyun, Cong Chunxiao, Brehm John A, Zhang Zhaowei, Niu Lin, Chen Yu, Zhou Yao, Wang Yanlong, Liu Fucai, Zhu Chao, Yu Ting, Suenaga Kazu, Mishra Rohan, Pantelides Sokrates T, Zhu Zhen-Gang, Gao Weibo, Liu Zheng, Zhou Wu
School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8565, Japan.
Adv Mater. 2020 Mar;32(11):e1906536. doi: 10.1002/adma.201906536. Epub 2020 Feb 6.
Internal magnetic moments induced by magnetic dopants in MoS monolayers are shown to serve as a new means to engineer valley Zeeman splitting (VZS). Specifically, successful synthesis of monolayer MoS doped with the magnetic element Co is reported, and the magnitude of the valley splitting is engineered by manipulating the dopant concentration. Valley splittings of 3.9, 5.2, and 6.15 meV at 7 T in Co-doped MoS with Co concentrations of 0.8%, 1.7%, and 2.5%, respectively, are achieved as revealed by polarization-resolved photoluminescence (PL) spectroscopy. Atomic-resolution electron microscopy studies clearly identify the magnetic sites of Co substitution in the MoS lattice, forming two distinct types of configurations, namely isolated single dopants and tridopant clusters. Density functional theory (DFT) and model calculations reveal that the observed enhanced VZS arises from an internal magnetic field induced by the tridopant clusters, which couples to the spin, atomic orbital, and valley magnetic moment of carriers from the conduction and valence bands. The present study demonstrates a new method to control the valley pseudospin via magnetic dopants in layered semiconducting materials, paving the way toward magneto-optical and spintronic devices.
研究表明，二硫化钼（MoS）单层中磁性掺杂剂诱导的内禀磁矩可作为调控谷塞曼分裂（VZS）的新手段。具体而言，报道了成功合成磁性元素钴（Co）掺杂的MoS单层，通过控制掺杂剂浓度来调控谷分裂的大小。偏振分辨光致发光（PL）光谱显示，在7 T磁场下，Co浓度分别为0.8%、1.7%和2.5%的Co掺杂MoS单层的谷分裂分别达到3.9、5.2和6.15 meV。原子分辨率电子显微镜研究清楚地确定了Co在MoS晶格中的替代磁位点，形成了两种不同的构型，即孤立的单掺杂剂和三掺杂剂团簇。密度泛函理论（DFT）和模型计算表明，观察到的增强VZS源于三掺杂剂团簇诱导的内禀磁场，该磁场与导带和价带中载流子的自旋、原子轨道和谷磁矩耦合。本研究展示了一种通过层状半导体材料中的磁性掺杂剂来控制谷赝自旋的新方法，为磁光和自旋电子器件的发展铺平了道路。
