The magnetism of intrinsic structural defects in monolayer MoTe2

Accepted Manuscript The magnetism of intrinsic structural defects in monolayer MoTe2 Yi Li, Yaqiang Ma, Mingyu Zhao, Qian Sun, Yawei Dai, Jing Liu, Huiting Li, Xianqi Dai PII:

S0925-8388(17)34216-0

DOI:

10.1016/j.jallcom.2017.12.041

Reference:

JALCOM 44127

To appear in:

Journal of Alloys and Compounds

Received Date: 30 September 2017 Revised Date:

3 December 2017

Accepted Date: 4 December 2017

Please cite this article as: Y. Li, Y. Ma, M. Zhao, Q. Sun, Y. Dai, J. Liu, H. Li, X. Dai, The magnetism of intrinsic structural defects in monolayer MoTe2, Journal of Alloys and Compounds (2018), doi: 10.1016/ j.jallcom.2017.12.041. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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The Magnetism of Intrinsic Structural Defects in Monolayer MoTe2 Yi Lia , Yaqiang Maa, Mingyu Zhaoa, Qian Suna, Yawei Daic, Jing Liua, Huiting Lia, a

b

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and Xianqi Daia,b,* College of Physics and Material Science, Henan Normal University, Xinxiang 453007, China

School of Physics and Electronic Engineering, Zhengzhou Normal University, Zhengzhou, Henan 450044, China c

Physics Department, The university of Hong Kong, Pokfulam Road, Hong Kong *Corresponding author. E-mail address: [email protected] (Xianqi Dai).

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Abstract

Monolayer MoTe2 exhibits excellent electronic properties which can be widely utilized in

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opto- and nanoelectronic fields. Intrinsic defects are commonly formed in MoTe2 growth, which would significantly influence the nature of the material. We systematically studied the electronic and magnetic properties of intrinsic defects including point defects and boundaries in monolayer MoTe2 by means of first-principles calculations based on density functional theory (DFT). Results show that the defective structures could effectually induce magnetic moment with the exception of VTe, VTe2, VMoTe3, VMoTe6 as well as the 4|4a boundary. Briefly speaking, boundary defects are

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easier to induce magnetic generation than point defects. Additionally, the electronic structures of the defective structures were systematically analyzed to understand the origin of the observed magnetism. Moreover, different application foreground could be anticipated through the modulation of defect structures, for instance, 4|4b and 8|8b boundaries can form a metallic interface as well as the 6|6a structure can form spin gapless semiconductor(SGS), respectively.

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Our calculated results suggest that intrinsic structural defects in monolayer MoTe2 could open a

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new platform to extend the application in spintronics and electronics. Keywords: monolayer MoTe2; defects; electronic properties; magnetism

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1.

Introduction In the wake of the first mechanical exfoliation of graphene in 2004[1], atomically thin

two-dimensional (2D) layered materials have attracted an upsurge of interest during the past decade. As a result, one kind of vital 2D materials 2D transition metal dichalcogenides (TMDs) is

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coming into play on account of their numerous fascinating properties that are potentially important for a wide range of applications in next-generation nanoelectronic devices[2-4]. Differ from the vanishing band gap of graphene, group-

TMDs, which in a common form of MX2 (M= Mo, W;

X= S, Se, Te), have a sizable intrinsic band gap (1.4-2.0 eV). It has been discovered a remarkable

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intrinsic properties by optical and transport experiments[5-14], and superior to graphene in many areas.

The 2D TMDs have gained world wide interest both experimentally and theoretically during

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recent years. Typical TMDs include MoS2, MoSe2, and MoTe2 etc.. Bulk MoTe2 is an indirect band gap semiconductor[15,16], but when the thickness decreases to monolayer, it exhibits a direct band gap of 1.10 eV as a consequence of the quantum confinement effect. In 2011, MoTe2 single layers have been firstly obtained through liquid exfoliating in the experiments[17]. This monolayer material exhibits a phonon-limited room-temperature mobility greater than that of MoS2, extends the spectral range of atomically thin direct-gap materials from the visible to the near-infrared[18]. However, the non-magnetism limits its application spintronics. Whereafter,

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large-area monolayer TMDs can now be exfoliated via chemical vapor transport(CVT) and chemical vapor deposition(CVD) [19], making it has wider and better applications such as logic transistors, superconductors, and valley optoelectronics[20]. Structural defects are ubiquitous when large-scale single layer materials were synthesized

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under fluctuating growth conditions by using the CVD or CVT method. Previous experimental studies have shown that a number of different defects exist in the monolayer TMDs, covering point defects and boundaries[21,22]. The defects could significantly influence the geometric,

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mechanical, optical, thermal, and electrical properties of the material. Furthermore, intrinsic structural defects in 2D TMDs provide an exciting opportunity to modulate the local properties on new application. In recent years, the electronic properties of the defects of MoS2, MoSe2, WS2, etc. have been intensively studied in both experimental and theoretical research[16-17,19,21]. But to the best of our knowledge, few literatures have reported on the combination of magnetic and electronic structures for intrinsic structural defects in monolayer MoTe2, thus little is known about it up to now. Motivated by the questions above, in this article, we have systematically studied the electronic and magnetic properties of intrinsic defects including point defects and boundaries in monolayer MoTe2 by means of DFT simulations, and emphatically analyzed that how different boundaries with distinct dislocation core structures influence the surrounding atoms and alter the magnetism

ACCEPTED MANUSCRIPT of MoTe2 monolayer. Furthermore, we systematically expounded the similarities and differences in the electronic structure of different intrinsic defects, which suggests that intrinsic structural defects in monolayer MoTe2 could optimize the material properties and enable unprecedented functionalities. 2.

Computational Methods

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The DFT calculations were mainly performed with the Vienna Ab initio Simulation Package (VASP) [23,24], using the projector-augmented wave (PAW) method to describe electron-ion interactions[25,26].

The

exchange-correlation

potentials

was

described

through

the

Predew-Burke-Ernzerhof (PBE) functional of generalized gradient approximation (GGA)

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formalism with a plane-wave kinetic energy cutoff of 480 eV[26]. A vacuum spacing of 15 Å along z direction was used to keep the interlayer coupling negligible[27], and sufficient Monkhorst-Pack[28] k-points of gamma-centered in the Brillouin zone are used along periodic

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directions to ensure energy convergence. All structures are relaxed using conjugate gradient techniques as implemented in the VASP code until the forces on each atom is smaller than 0.01 eV/Å. All of structural figures and charge density drawings are produced by VESTA package[29]. 3.

Result and discussion

3.1. The magnetism of intrinsic point defects in MoTe2 monolayer

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Before we discuss intrinsic point defects, the pristine MoTe2 monolayer should be introduced firstly. With different stacking orders, MoTe2 have different phase structures (e.g., 2H, 1T, 1T’) and 2H phase is the most stable case at room temperature which composed of that each Mo atom is prismatically coordinated to six surrounding Te atoms (Fig.1)[20]. So, we only discuss the 2H-MoTe2 in the following. After optimizing, the lattice constants of monolayers MoTe2 is 3.52 Å

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and a nonmagnetic semiconductor with direct band gaps of 1.163 eV is obtained, which are in well agreement with experimental and other DFT values[20,30].

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The simplest and most common point defects in 2D materials are vacancies and the antisites. Fig. 2 shows the optimized five types of point defective structures in this paper, including single tellurium vacancy (VTe), double tellurium vacancies (VTe2), vacancy complex of a Mo atom and a triad of Te within one plane (VMoTe3), vacancy complex of a Mo atom and all six of its bonded neighbors (VMoTe6), and antisite defects with a Mo atom occupying two Te atoms (MoTe2). These five varieties of intrinsic point defects are observed regular in synthetic. It's worth noting that VMo is not in this list because of its tendency to complex with tellurium vacancies. After optimization, all the defect structures do not undergo significant distortion from the pristine lattice and retain the trigonal symmetry. Next, the electronic properties of the point defects in MoTe2 monolayer are studied. The total density of states (DOS) of the five point defects as well as pristine structure is shown in Fig. 3. Compared to the pristine single layer MoTe2, some impurity states appear in the band gap of all

ACCEPTED MANUSCRIPT five types of defects. All the vacancy defects including VTe, VTe2, VMoTe3, VMoTe6 display spin unpolarized with symmetry DOS between the spin-up and spin-down, and the total magnetic moment of the system is zero, suggesting that vacancy defects do not induce magnetism in MoTe2 monolayer. However, the antisite defect MoTe2 induce a biggish spin polarization and result in an asymmetric DOS between spin-up and spin-down near the Fermi energy, leading to the formation of local magnetic moments of 1.93 µB in the single layer MoTe2 (Fig. 3). To further explore the

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origin of magnetism, we have plotted the charge spin density and projected DOS of MoTe2 monolayer with MoTe2 defect (Fig. 4). The main contribution to the spin polarization results from the nearest Mo atoms, and the other atoms in the supercell almost do not have any contribution to it (Fig. 4a). The magnetic moment is mainly contributed by the p orbital of the Te atoms and the d orbital of Mo atoms with an asymmetric spin-up and spin-down DOS near the Fermi level (Fig.

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4b).

3.2. The magnetism of boundary defects in MoTe2 monolayer

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With the exception of the point defects, extended one-dimensional (1D) defects such as boundary defects are constantly observed in 2D materials. In the synthesis of MoTe2 monolayer by CVD methods, where two grains meet each other by propagating growth fronts are forming boundaries. Be in contrast with the graphene, the boundary defects are considerably complicated, because as atoms have movement, the structure relaxing extend in third dimension, to form dreidel shaped polyhedra with a variety of ringed motifs.

Extended one-dimensional (1D) defects such as boundary defects are constantly observed in

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2D materials which were observed in CVD growth MoSe2 experimentally. A diverse range of dislocation cores ascribe to the special bonding characteristics between Mo and Te in monolayer MoTe2, which the boundaries could be categorized into three main areas (tilt, zigzag and armchair). Fig. 5 shows the structures of the nine types of boundaries considered in this work, which are

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named according to the number of sides of the ringed dislocation core at the boundary. To distinguish the different atomic arrangement in the rings, lower-case letters were added behind. For instance, the dislocation core of 5|7 boundaries is arranged repeatedly by five- and seven- fold

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rings. In addition, the letter ‘a’ was used to mark off the central anion and ‘b’ for the central cation. To appraise the influence of different defects on the electronic structure, the electronic structures and magnetism of each boundary defects will be analyzed by classifications. 3.2.1. Tilt boundary defects in MoTe2 monolayer The 5|7a boundary of monolayer MoTe2 is deleting half of an armchair atoms and

reconnecting all of the resultant dangling bonds seamlessly with Te-Te homoelemental bonds. Removing an inverted half-line yields an inverse dislocations 5|7b, with Mo-Mo homoelemental bonds. Spin polarized calculations suggest that 5|7a and 5|7b introduce strong spin polarization and lead to the formation of local moments (0.58 µB and 0.52 µB) as shown in Table 1. To understand clearly why 5|7 boundaries in MoTe2 monolayer are magnetic, we calculate the electronic structure and plot the spin charge density and DOS ( Fig. 6a, c, d and f). The spin polarization in 5|7a is mainly on three Mo atoms of the 7-fold rings, particularly on the vertices

ACCEPTED MANUSCRIPT Mo-1 atoms as marked in Fig. 6. The spin polarization in 5|7b sits mostly on the Mo-Mo bond and its four nearest-neighbor Mo atoms. Both 5|7a and 5|7b displays ferromagnetic coupling. In order to analyze the main source of the magnetic moment, we calculated the charge transfer in 4p, 5s, and 4d orbital of monoatomic Mo atom (Table 1). At the same time, we compared the difference between spin-up and spin-down of Mo atom 4d orbital and the magnetic moment of a single Mo atom (Fig. 7). The results showed that the magnetism is come from the 4d orbital of Mo atom

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around the boundary.

To understand the different magnetic effects of monoatomic Mo at the boundary, we have analyzed the total DOS of 5|7a and 5|7b. There are some impurity states in deep energy level, and an asymmetric spin-up and spin-down DOS near the Fermi energy, which indicates both 5|7a and 5|7b are magnetic. The Mo-1 atom makes more contribution to the total magnetic moment of

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single Mo atom (Fig. 6c), it also can be supported by the magnetic moment of single Mo atom as shown in Table 1. Differently, in 5|7b, the magnetic moment of Mo-2 is greater than Mo-3 and

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Mo-1. Different magnetism populations between 5|7a and 5|7b could be attributed to the coordination number which the Mo-1 is 6-fold-coordinated in 5|7a but 5-fold-coordinated in 5|7b. The positive value of charge density difference along x direction of monolayer MoTe2 5|7a and 5|7b indicates charge accumulation at the position, and the negative value means charge depletion, the vertical red short dash line represent the intermediate position of the boundary (Fig. 6b,e). It is obvious that the charge redistributes mainly on the boundary. More charge transfer around the

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boundary suggests a strong ionic bond, leading to the charge enrichment at the boundary.

Table 1. calculated magnetic moment of boundary system (Mtot in µB), total charge transfer of single Mo atom (∆eatom in e), charge transfer in 4p, 5s, and 4d orbital of Mo atom (∆e4p, ∆e5s, ∆e4d in e), difference between spin-up and spin-down of Mo atom 4d orbital (∆ed in e), magnetic moment of

Boundary

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Type

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single Mo atom(Matom in µB).

Tilt

5|7a

5|7b

Armchair

Zigzag

4|8

4|4a

Mtot

0.58

0.52

0.43

0.00

Atom

∆eatom

∆e4p

∆e5s

∆e4d

∆ed

Matom

Mo-1

1.10

-0.37

0.65

0.82

0.22

0.29

Mo-2

0.97

-0.40

0.64

0.74

0.08

0.10

Mo-3

1.02

-0.39

0.65

0.76

0.03

0.05

Mo-1

0.98

-0.40

0.65

0.72

0.02

0.02

Mo-2

0.78

-0.39

0.60

0.58

0.07

0.08

Mo-3

0.98

-0.40

0.65

0.73

0.08

0.07

Mo-1

0.86

-0.35

0.63

0.58

0.04

0.04

Mo-2

0.98

-0.39

0.65

0.72

0.10

0.09

Mo-3

1.04

-0.38

0.65

0.77

0.06

0.06

Mo-1

0.87

-0.43

0.62

0.68

0.00

0.00

0.48

6|6b

0.32

8|8a

1.38

8|8b

-0.40

0.65

0.72

0.00

0.00

Mo-3

0.94

-0.41

0.64

0.70

0.00

0.00

Mo-1

1.26

-0.34

0.67

0.94

0.73

0.83

Mo-2

0.99

-0.41

0.64

0.76

0.14

0.14

Mo-3

0.97

-0.41

0.65

0.73

0.03

0.03

Mo-1

0.90

-0.42

0.64

0.69

0.50

0.45

Mo-2

1.03

-0.38

0.66

0.76

-0.03

0.04

Mo-3

0.96

-0.40

0.65

0.71

0.02

0.01

Mo-1

0.81

-0.39

0.60

0.60

0.03

0.08

Mo-2

1.01

-0.38

0.66

0.74

0.07

0.13

Mo-3

0.96

-0.41

0.65

0.72

0.01

0.03

Mo-1

1.04

-0.40

0.64

0.80

0.15

0.16

Mo-2

1.03

-0.39

0.65

0.76

-0.01

0.01

Mo-1

1.12

-0.39

0.64

0.86

1.19

1.36

Mo-2

0.96

-0.40

0.64

0.71

0.01

0.01

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0.85

6|6a

0.98

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1.18

4|4b

Mo-2

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3.2.2. Armchair boundary defects in MoTe2 monolayer

The 4|8 boundary of monolayer MoTe2 is claving two parallel zigzag atomic chains from

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perfect lattice and splitting joint. Spin polarized calculations suggest that 4|8 boundary induce spin polarization and lead to the formation of local moments of about 0.43 µB (Table 1). The spin charge density and DOS was calculated and exhibited in Fig. 8a and c for limpidness of its electronic and magnetic properties. 4|8 boundary has a ferromagnetic ground state, which the spin

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polarization is mainly located in three Mo atoms of the 8-fold rings and its two nearest-neighbor Mo atoms beyond the defect.

To understand the different magnetic effects of individual Mo atoms in the boundary, we have

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analyzed the partial DOS of 4|8 boundary (Fig. 8c). There are impurity states near the top of the conduction band, giving rise to an asymmetry between spin-up and spin-down channels near the Fermi energy, which indicates that 4|8 boundary of monolayer MoTe2 is magnetic. The contribution to the total magnetic moment of Mo-2 with 6 coordination numbers is greater than Mo-3 and Mo-1 with 5 coordination number, which can be supported by the magnetic moment of single Mo atom as shown in Table 1. Fig. 8b is the charge density difference along x direction of monolayer MoTe2 4|8 boundary. It is evident that the symmetric charge redistribution is mainly on the boundary. More charge transfer around the boundary suggests a strong ionic bond, resulting in the charge accumulation at the boundary. 3.2.3. Zig-zag boundary defects in MoTe2 monolayer Considering the arrangement of atoms in such boundary defects, there are six kinds of

ACCEPTED MANUSCRIPT structures named as 4|4a, 4|4b, 6|6a, 6|6b, 8|8a, 8|8b and exhibited in Fig.9, 10, 11. The electronic structure of them would be discussed one by one in the following text. The mirror twin boundaries 4|4 of monolayer MoTe2 is parallel to the zigzag direction of the MoTe2 lattice and composed of 4-fold rings with point sharing at a common Te2 or Mo site. Spin polarized calculations suggest that 4|4a is nonmagnetic and 4|4b is magnetic (1.18 µB) as shown in Table 1. We calculate the electronic structure then plot the spin charge density and DOS (Fig 9a, c, the boundary central Mo-1 and its four nearby Mo-2 and Mo-3 atoms.

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d and f). The 4|4b boundary has a ferromagnetic ground state, the spin polarization is mainly on The 4|4b boundary of monolayer MoTe2 is metallic and magnetic (Fig. 9f). This can be explained in the following aspects as that the Te atoms at this boundary retain the regular 3-fold coordination, but the Mo atoms change from the regular 6-fold coordination to 8-fold coordination.

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The variation of coordination number at the boundary introduces mid-gap states. It is worth noting that the 4|4b defective structure can serve as a perfect one-dimensional metallic wires embedded

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in the other semiconducting MoTe2, which could provide more functionalities by forming intrinsic electronic heterostructures in single layer MoTe2.

Mo-1 atom of 4|4b boundary has the most coordination number and the largest magnetic moment compared with the Mo-2 and the Mo-3 atom with regular 6-fold coordination. The detailed parameters of the magnetic moment of single Mo atom are given in the Table 1. Differently, the DOS of 4|4s shows a symmetric spin-up and spin-down near the Fermi energy. Nonmagnetic boundary 4|4a is stitched with Te atoms at the boundary which hardly affects the

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charge redistribution of Mo atoms and the electronic properties of Te atoms are very close to pristine monolayer MoTe2.

The charge density difference along x direction of 4|4a and 4|4b shows that the charge redistributes mainly on the boundary (Fig. 9b,e). The charge of 4|4a has a symmetric

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redistribution at the boundary. In both of 4|4a and 4|4b, charges mainly accumulate on the Te atom around boundary. More charge transfer around the boundary suggests a strong ionic bond, leading to the charge accumulation near the interface.

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For 6|6 defective structure of monolayer MoTe2, it was building by removing two armchair

atoms and reconnecting all of the resultant dangling bonds seamlessly. The Te-Te homoelemental bounds and Mo-Mo catenation make a distinction between the 6|6a structure and 6|6b beyond the boundary. Spin polarized calculations suggest that 6|6a and 6|6b induce spin polarization and lead to a local moments of 0.85µB and 0.48µB (Table 1). The spin charge density and DOS are given to explore why 6|6 boundaries in MoTe2 monolayer are magnetic (Fig. 10 a, c, d and f). The spin polarization in 6|6a is mainly on two Mo atoms of the 6-fold rings. In 6|6b it sits mostly on the Mo-Mo bond and its four nearby Mo atoms. Both 6|6a and 6|6b display ferromagnetic coupling. There are impurity states in deep energy level, and an asymmetric DOS between spin-up and spin-down near the Fermi energy, which indicates both 6|6a and 6|6b are magnetic (Fig. 10c). Importantly, what can be directly seen from the spin gapless band structures of 6|6a is that no energy is required to excite electrons from the VBM to the CBM. In SGS, not only the excited

ACCEPTED MANUSCRIPT electrons but also the holes can be easily spin polarized, which could have wide applications for creation and manipulation of spin-polarized carriers in spintronics. At the 6|6a boundary, Mo-1 atom makes more contribution to the total magnetic moment than the Mo-2 and Mo-3 atom with the same coordination number. At 6|6b, the magnetic moment of Mo-2 with 6-fold coordination is greater than Mo-1 with 5-fold coordination and the farthest Mo-3. It can be supported by the data of Table 1.

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The charge density difference along x direction of 6|6a and 6|6b shows that the symmetric charge redistribution is mainly on the boundary (Fig. 10b,e). In both of 6|6a and 6|6b, charges mainly accumulate on the Te atom around boundary. More charge transfer around the boundary reveals the charge accumulation near the interface.

Mirror twin boundaries 8|8 is another zigzag directional line defect of monolayer MoTe2

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which composed of 8-fold rings with point sharing at a common two Te2 or two Mo site. This type of boundaries is free of any homo-elemental bonding. 8|8a and 8|8b induce a spin polarization and

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lead to the formation of local moments (0.32 µB and 1.39 µB) as shown in Table 1. We calculate the electronic structure then plot the spin charge density and DOS (Fig. 11 a, c, d and f). 8|8a boundary has a ferromagnetic ground state and the spin polarization is mainly located on four Mo atoms of the 8-fold rings and its two nearest-neighbor Mo atoms. In 8|8b the spin polarization sits mostly on four Mo atoms of the 8-fold rings with displaying ferromagnetic coupling. There are some impurity states in deep energy level, resulting in an asymmetric spin-up and spin-down DOS near the Fermi energy, which indicates 8|8a introduce magnetism into the system

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(Fig. 11c). 8|8b has the similar metallic density of states to 4|4a (Fig. 11f), which can serve as a 1D metallic wires embedded in the otherwise semiconducting MoTe2, and forming intrinsic electronic heterostructures in single layer MoTe2. In 8|8a and 8|8b, with the same coordination number, the closer to the boundary center, the more contribution to the total magnetic moment of

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the Mo atom (Fig. 11c,f and Table 1) .

The charge density difference along x direction of 8|8a and 8|8b shows that the charge redistributes mainly on the boundary, and mainly accumulates on the Te atom around boundary

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(Fig. 11b, e). More charge transfer around the boundary suggests a strong ionic bond, leading to the charge accumulation near the interface. 4.

Conclusion

In summary, we investigated the electronic and magnetic properties of five different

configurations of point defects, and nine different structures of boundary defects in monolayer MoTe2 based on DFT calculations. Our findings can be summarized into following points. For the point defects, only antisite defect MoTe2 in single layer MoTe2 can induce spin-polarization, and other four vacancy defects VTe, VTe2, VMoTe3, VMoTe6 is nonmagnetic. For the boundary defects, with the exception of 4l4a, other types of boundaries including 5|7a, 5|7b, 4|8, 4|4b, 6|6a, 6|6b, 8|8a and 8|8b induce spin polarization and lead to the formation of local

ACCEPTED MANUSCRIPT moments, which is come from the 4d orbital of Mo atom around the boundary (Fig. 8). Compared with the nonmagnetic pristine MoTe2 monolayer, the introduction of magnetic defects makes it having wider and better applications for spintronics devices. For the magnetic boundary defects, the principle of the magnetic moment magnitude for Mo atoms in different positions can be summarized as that the coordination number of Mo atom and its distance from the boundary center have a major impact on it. With the same coordination number, the smaller distance of Mo

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atom to boundary, the larger magnetic moment of Mo atom. When the coordination number is different, the Mo atom has the larger magnetic moment with the more coordination number. It is worth noting that 6|6a shows a spin gapless band structures, which could have wide applications for creation and manipulation of spin-polarized carriers in spintronics. The 4|4b and 8|8b boundary shows a metallic band structure, which can serve as a perfect one-dimensional metallic

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wires embedded in the other semiconducting MoTe2 and could provide more functionalities by forming intrinsic electronic heterostructures in single layer MoTe2. Our results could shed light on

Acknowledgments

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the design of novel nano- and magnetic electronics based on MoTe2 by structural modulation.

This work was financially supported by the National Natural Science Foundation of China (Grant No.61674053, U1404109 and 11504334) and by the High Performance Computing Center of Henan Normal University.

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[21] W. Zhou, X. Zou, S. Najmaei, Intrinsic structural defects in monolayer molybdenum disulfide,

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Nano Letters. 13 (2013) 2615.

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ACCEPTED MANUSCRIPT Physical Review Letters. 77 (1996) 3865. [27] A. Bermudez, F. Jelezko, M.B. Plenio, Electron-mediated nuclear-spin interactions between distant nitrogen-vacancy centers, Physical Review Letters. 107 (2011) 150503. [28] D.J. Chadi, Special points for Brillouin-zone integrations, Physical Review B Condensed Matter. 16 (1977) 5188--5192. wxWidgets, IUCr News Lett. 7 (2006) 106-119.

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[29] K. Momma, F. Izumi, An integrated three-dimensional visualization system VESTA using [30] Y. Ma, Y. Dai, M. Guo, Electronic and magnetic properties of perfect, vacancy-doped, and nonmetal adsorbed MoSe2, MoTe2 and WS2 monolayers, Physical Chemistry Chemical

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Physics Pccp. 13 (2011) 15546.

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Fig. 1. (a) Top and (b) side views of atomic structures of MoTe2 monolayer. Purple and yellow balls represent Mo and Te atoms respectively in this text. The red dash line means the lattice of MoTe2

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primitive cell.

Fig. 2. Top and side views of fully relaxed structural models of the five types of point defects: VTe, VTe2, VMoTe3, VMoTe6, and MoTe2. The purple, yellow, and green balls represent Mo, top layer Te, and bottom layer Te, respectively.

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Fig. 3. The total DOS of the five types of point defects, and pristine structure of monolayer MoTe2.

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The Fermi level is set to zero in this text.

Fig. 4. (a) Top view of the isosurface plot of the charge density of MoTe2 monolayer with MoTe2

vacancy. Pink and green isosurfaces represent positive and negative spin densities, respectively. All isosurfaces of this text are set 0.004eÅ-3. (b) The projected DOS of MoTe2 monolayer with MoTe2 vacancy.

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Fig. 5. Fully relaxed structural schema of the nine types of monolayer MoTe2 boundaries

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considered in this work, the red dashed frame denotes the position of the boundary.

Fig. 6. The spin charge density (a, d), charge density difference along x direction (b, e), total DOS (c, f) of 5|7a and 5|7b, respectively.

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Fig. 7. Comparison of the difference between spin-up and spin-down of Mo atom 4d orbital (∆ed) and

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the magnetic moment of a single Mo atom(Matom).

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Fig. 8. The spin charge density (a), charge density difference along x direction (b), total DOS (c) of 4|8.

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Fig. 9. The spin charge density (a, d), charge density difference along x direction (b, e), total DOS

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(c, f) of 4|4a and 4|4b, respectively.

Fig. 10. The spin charge density (a, d), charge density difference along x direction (b, e), total DOS (c, f) of 6|6a and 6|6b, respectively.

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Fig. 11. The spin charge density (a, d), charge density difference along x direction (b, e), total DOS

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(c, f) of 8|8a and 8|8b, respectively.

ACCEPTED MANUSCRIPT The boundary defects are easier to induce magnetic generation.

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The magnetic boundaries induce spin polarization.

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Magnetism of Mo atoms is related to the coordination number and distance.

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Many applications could be anticipated through modulating defect structures.

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