Synthesis of Co‐Doped MoS<sub>2</sub> Monolayers with Enhanced Valley Splitting
Jiadong Zhou, Junhao Lin, Hunter Sims, Chongyun Jiang, Chunxiao Cong, John A. Brehm, Zhaowei Zhang, Lin Niu, Yu Chen, Yao Zhou, Yanlong Wang, Fucai Liu, Chao Zhu, Ting Yu, Kazu Suenaga, Rohan Mishra, Sokrates T. Pantelides, Zhen‐Gang Zhu, Weibo Gao, Zheng Liu, Wu Zhou
Abstract
Abstract Internal magnetic moments induced by magnetic dopants in MoS 2 monolayers are shown to serve as a new means to engineer valley Zeeman splitting (VZS). Specifically, successful synthesis of monolayer MoS 2 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 2 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 2 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.