中国物理B ›› 2017, Vol. 26 ›› Issue (2): 27103-027103.doi: 10.1088/1674-1056/26/2/027103

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Structural, electronic, and magnetic properties of vanadium atom-adsorbed MoSe2 monolayer

Ping Liu(刘萍), Zhen-Zhen Qin(秦真真), Yun-Liang Yue(乐云亮), Xu Zuo(左旭)   

  1. College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China
  • 收稿日期:2016-09-05 修回日期:2016-11-06 出版日期:2017-02-05 发布日期:2017-02-05
  • 通讯作者: Xu Zuo E-mail:xzuo@nankai.edu.cn
  • 基金资助:

    Project supported by the National Basic Research Program of China (Grant No. 2011CB606405), the CAEP Microsystem and THz Science and Technology Foundation, China (Grant No. CAEPMT201501), and the Science Challenge Project, China (Grant No. JCKY2016212A503).

Structural, electronic, and magnetic properties of vanadium atom-adsorbed MoSe2 monolayer

Ping Liu(刘萍), Zhen-Zhen Qin(秦真真), Yun-Liang Yue(乐云亮), Xu Zuo(左旭)   

  1. College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China
  • Received:2016-09-05 Revised:2016-11-06 Online:2017-02-05 Published:2017-02-05
  • Contact: Xu Zuo E-mail:xzuo@nankai.edu.cn
  • Supported by:

    Project supported by the National Basic Research Program of China (Grant No. 2011CB606405), the CAEP Microsystem and THz Science and Technology Foundation, China (Grant No. CAEPMT201501), and the Science Challenge Project, China (Grant No. JCKY2016212A503).

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摘要：

Using the first-principles calculations, we study the structural, electronic, and magnetic properties of vanadium adsorbed MoSe2 monolayer, and the magnetic couplings between the V adatoms at different adsorption concentrations. The calculations show that the V atom is chemically adsorbed on the MoSe2 monolayer and prefers the location on the top of an Mo atom surrounded by three nearest-neighbor Se atoms. The interatomic electron transfer from the V to the nearest-neighbor Se results in the polarized covalent bond with weak covalency, associated with the hybridizations of V with Se and Mo. The V adatom induces local impurity states in the middle of the band gap of pristine MoSe2, and the peak of density of states right below the Fermi energy is associated with the V-dz2 orbital. A single V adatom induces a magnetic moment of 5 μB that mainly distributes on the V-3d and Mo-4d orbitals. The V adatom is in high-spin state, and its local magnetic moment is associated with the mid-gap impurity states that are mainly from the V-3d orbitals. In addition, the crystal field squashes a part of the V-4s electrons into the V-3d orbitals, which enhances the local magnetic moment. The magnetic ground states at different adsorption concentrations are calculated by generalized gradient approximations (GGA) and GGA+U with enhanced electron localization. In addition, the exchange integrals between the nearest-neighbor V adatoms at different adsorption concentrations are calculated by fitting the first-principle total energies of ferromagnetic (FM) and antiferromagnetic (AFM) states to the Heisenberg model. The calculations with GGA show that there is a transition from ferromagnetic to antiferromagnetic ground state with increasing the distance between the V adatoms. We propose an exchange mechanism based on the on-site exchange on Mo and the hybridization between Mo and V, to explain the strong ferromagnetic coupling at a short distance between the V adatoms. However, the ferromagnetic exchange mechanism is sensitive to both the increased inter-adatom distance at low concentration and the enhanced electron localization by GGA+U, which leads to antiferromagnetic ground state, where the antiferromagnetic superexchange is dominant.

关键词: V-adatom, MoSe2 monolayer, magnetic moment, magnetic coupling, first-principles calculation

Abstract:

Using the first-principles calculations, we study the structural, electronic, and magnetic properties of vanadium adsorbed MoSe2 monolayer, and the magnetic couplings between the V adatoms at different adsorption concentrations. The calculations show that the V atom is chemically adsorbed on the MoSe2 monolayer and prefers the location on the top of an Mo atom surrounded by three nearest-neighbor Se atoms. The interatomic electron transfer from the V to the nearest-neighbor Se results in the polarized covalent bond with weak covalency, associated with the hybridizations of V with Se and Mo. The V adatom induces local impurity states in the middle of the band gap of pristine MoSe2, and the peak of density of states right below the Fermi energy is associated with the V-dz2 orbital. A single V adatom induces a magnetic moment of 5 μB that mainly distributes on the V-3d and Mo-4d orbitals. The V adatom is in high-spin state, and its local magnetic moment is associated with the mid-gap impurity states that are mainly from the V-3d orbitals. In addition, the crystal field squashes a part of the V-4s electrons into the V-3d orbitals, which enhances the local magnetic moment. The magnetic ground states at different adsorption concentrations are calculated by generalized gradient approximations (GGA) and GGA+U with enhanced electron localization. In addition, the exchange integrals between the nearest-neighbor V adatoms at different adsorption concentrations are calculated by fitting the first-principle total energies of ferromagnetic (FM) and antiferromagnetic (AFM) states to the Heisenberg model. The calculations with GGA show that there is a transition from ferromagnetic to antiferromagnetic ground state with increasing the distance between the V adatoms. We propose an exchange mechanism based on the on-site exchange on Mo and the hybridization between Mo and V, to explain the strong ferromagnetic coupling at a short distance between the V adatoms. However, the ferromagnetic exchange mechanism is sensitive to both the increased inter-adatom distance at low concentration and the enhanced electron localization by GGA+U, which leads to antiferromagnetic ground state, where the antiferromagnetic superexchange is dominant.

Key words: V-adatom, MoSe2 monolayer, magnetic moment, magnetic coupling, first-principles calculation

中图分类号:  (Density functional theory, local density approximation, gradient and other corrections)

  • 71.15.Mb
71.20.-b (Electron density of states and band structure of crystalline solids) 73.20.Hb (Impurity and defect levels; energy states of adsorbed species) 75.70.Ak (Magnetic properties of monolayers and thin films)