Mao-Peng Miao, Nanshu Liu, Wen-Hao Zhang, Jian-Wang Zhou, Dao-Bo Wang, Cong Wang, Wei Ji, and Ying-Shuang Fu
Abstract:
Noncollinear magnetic orders in monolayer van der Waals magnets are crucial for probing delicate magnetic interactions under minimal spatial constraints and advancing miniaturized spintronic devices. Despite their significance, achieving atomic-scale identification remains challenging. In this study, we utilized spin-polarized scanning tunneling microscopy and density functional theory calculations to identify spin-spiral orders in mono- and bi-layer NiI2, grown on graphene-covered SiC(0001) substrates. We discovered two distinct spin-spiral states with Q vectors aligning and deviating by 7° from the lattice direction, exhibiting periodicities of 4.54 and 5.01 times the lattice constant, respectively. These findings contrast with bulk properties and align closely with our theoretical predictions. Surprisingly, the finite sizes of monolayers induce incommensurability with the spin-spiral period, facilitating collective spin switching behavior under magnetic fields. Our research reveals intrinsic noncollinear magnetism at the monolayer limit with unprecedented resolution, paving the way for exploring novel spin phenomena.
Peigen Li, Nanshu Liu, Jihai Zhang, Shenwei Chen, Xuhan Zhou, Donghui Guo, Cong Wang, Wei Ji, and Dingyong Zhong
Abstract:
Single-layer heterostructures of magnetic materials are unique platforms for studying spin-related phenomena in two dimensions (2D) and have promising applications in spintronics and magnonics. Here, we report the fabrication of 2D magnetic lateral heterostructures consisting of single-layer chromium triiodide (CrI3) and chromium diiodide (CrI2). By carefully adjusting the abundance of iodine based on molecular beam epitaxy, single-layer CrI3–CrI2 heterostructures were grown on Au(111) surfaces with nearly atomic-level seamless boundaries. Two distinct types of interfaces, i.e., zigzag and armchair interfaces, have been identified by means of scanning tunneling microscopy. Our scanning tunneling spectroscopy study combined with density functional theory calculations indicates the existence of spin-polarized ground states below and above the Fermi energy localized at the boundary. Both the armchair and zigzag interfaces exhibit semiconducting nanowire behaviors with different spatial distributions of density of states. Our work presents a novel low-dimensional magnetic system for studying spin-related physics with reduced dimensions and designing advanced spintronic devices.
(2) Nanshu Liu, Si Zhou*, Jijun Zhao, Photoinduced spin injection and ferromagnetism in 2D group III monochalcogenides, J. Phys. Chem. Lett. 153, 590 (2022)
(3) Nanshu Liu, Si Zhou*, Jijun Zhao, Visible-light overall water splitting on g-C3N4 decorated by subnanometer oxide clusters, Mater. Today Phys., 16, 100312 (2021)
(4) Nanshu Liu, Yanyan Zhao, Si Zhou*, Jijun Zhao, CO2 reduction on p-block metal oxide overlayers on metal substrates—2D MgO as a prototype, J. Mater. Chem. A, 8, 5688 (2020)
(5) Nanshu Liu, Si Zhou*, Jijun Zhao, High-Curie-temperature ferromagnetism in bilayer CrI3 on bulk semiconducting substrates, Phys. Rev. Mater., 4, 094003 (2020)
(6) Nanshu Liu, Junfeng Zhang*, Si Zhou*, Jijun Zhao, Tuning the electronic properties of bilayer black phosphorene with the twist angle, J. Mater. Chem. C, 8, 6264 (2020)
(7) Shaofeng Li#, Yan Zhang#, Nanshu Liu#, et. al, Operando revealing dynamic reconstruction of NiCo carbonate hydroxide for high-rate energy storage, Joule, 4, 673 (2020)