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Cite this:Phys.Chem.Chem.Phys.,

2015, 17, 1831

Effects of 3d transition-metal doping on electronicand magnetic properties of MoS2 nanoribbons

Xiaoqing Tian,a Lin Liu,a Yu Du,*a Juan Gu,a Jian-bin Xub and Boris I. Yakobson*c

The electronic and magnetic properties of MoS2 nanoribbons doped with 3d transitional metals (TMs)

were investigated using first-principles calculations. Clean armchair MoS2 nanoribbons (AMoS2NRs) are

nonmagnetic semiconductors whereas clean zigzag MoS2 nanoribbons (ZMoS2NRs) are metallic magnets.

The 3d TM impurities tend to substitute the outermost cations of AMoS2NRs and ZMoS2NRs, which are in

agreement with the experimental results reported. The magnetization of the 3d-TM-impurity-doped

AMoS2NRs and ZMoS2NRs is configuration dependent. The band gap and carrier concentration of

AMoS2NRs can be tuned by 3d-TM doping. Fe-doped AMoS2NRs exhibit ferromagnetic characteristics and

the Curie temperature (TC) can be tuned using different impurity concentrations. Co-doped ZMoS2NRs are

strongly ferromagnetic with a TC above room temperature.

Introduction

The MoS2 monolayer is composed of three covalently bondedhexagonal atomic layers (S–Mo–S). Weak van der Waals interactionsexist between adjacent MoS2 monolayers. One important advantageof MoS2 is that the electronic and optical properties can be tuned byvarying the number of layers. The bulk MoS2 crystal is an indirectgap semiconductor with a band gap of 1.29 eV, whereas the MoS2

monolayer is a direct gap semiconductor with a band gap of1.90 eV.1,2 One-dimensional MoS2 has been synthesized inrecent experiments.3,4 Quasi-1D nanotubes and nanoribbonsof MoS2 share the honeycomb structure and are expected todisplay interesting electronic and magnetic properties arisingfrom quantum confinement effects.5,6 Defects and strain areexpected to modify the electronic and magnetic properties of theMoS2 monolayer and nanoribbons.7–10 MoS2 nanostructures aredoped with 3d TMs such as Fe, Co, and Ni to increase theircatalytic activities in hydrode sulfurization processes in the oilindustry.11,12 The magnetic and electronic properties of MoS2

nanoribbons could be tuned by 3d TM doping. Either 3d TMsubstrates or 3d TM nanoclusters could alter the electronicstructures of the MoS2 monolayer.13,14 We used a state-of-the-art

first-principles technique to study the electronic and magneticproperties of 3d TM (including Mn, Fe, and Co)-doped MoS2

nanoribbons with armchair- and zigzag-shaped edges.

Computational methods

Theoretical calculations were performed using the QuantumEspresso package,15 employing the GGA-PBE exchange correla-tion functional.16 The on-site Coulomb interaction GGA + U for3d TMs is used.17 The terms U and J are the on-site Coulombrepulsion and exchange interaction parameters, respectively.Typical values of U and J are 4.0 and 1.0 eV, respectively, forboth Mn and Fe;18,19 for Co, U and J are 3.3 and 1.0 eVrespectively. 40 Ry is used as the plane-wave basis set cutoff.The structural models of MoS2 nanoribbons are constructed bycutting a single-layered MoS2 with the desired edges andwidths. The 1-D periodic boundary condition was applied alongthe growth direction of the nanoribbons to simulate infinitely longnanoribbon systems; the length scales for the MoS2 nanoribbonsare defined in ref. 5. Specifically, the width of AMoS2NRs is definedby the number of dimmer columns whereas for ZMoS2NRs it isdefined by the number of Mo columns. A 1.6 nm thick vacuumlayer was used to eliminate longitudinal interactions between thesuper cells. For the 14-AMoS2NRs, the super cell contains in total168 atoms, and its in-plane size is around 3.5 nm (width)� 2.2 nm,which is large enough to avoid lateral image interactions. For10-ZMoS2NRs, the super cell contains in total 120 atoms, andits in-plane size is around 4.0 nm (width) � 0.7 nm, which isalso large enough to avoid lateral image interactions. A samplingof 12 uniformly distributed k-points along the 1-D Brillouin zone

a College of Physics and Technology and Shenzhen Key Laboratory of Sensor

Technology, Shenzhen University, Shenzhen 518060, Guangdong, P. R. China.

E-mail: duyu@szu.edu.cnb Department of Electronic Engineering and Materials Science and Technology

Research Center, The Chinese University of Hong Kong, Shatin, N.T.,

Hong Kong SAR, People’s Republic of Chinac Department of Mechanical Engineering and Materials Science,

Department of Chemistry, and the Smalley Institute for Nanoscale Science and

Technology, Rice University, Houston, Texas 77005, USA. E-mail: biy@rice.edu

Received 9th October 2014,Accepted 26th November 2014

DOI: 10.1039/c4cp04579c

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is employed for the MoS2 nanoribbons for both the zigzag andarmchair shaped edges.

Results and discussion

The structures of relaxed 14-AMoS2NRs (Fig. 1(a)) show a widthof around 2.1 nm. After structural optimization, the width of14-AMoS2NRs is increased by around 1.5 percent. There isobvious structural reconstruction to mitigate the truncationof chemical bonds at the edges. The S–Mo bonds in MoS2 arecomposed of partial covalent and ionic bonds similar to thebonds of ZnO. The oxidation state of the edgiest Mo is +1.63,which is 0.1 smaller than that of the interior Mo using theBader analysis method.20 The edgiest Mo atom is moved by0.3 Å inwards relative to the edgiest S atom. The bond length ofthe S–Mo bond is about 0.1 Å smaller than that of the interiorbond. The calculated spin-polarized density of states (SPDOS)of 14-AMoS2NRs is given in Fig. 1(b). The 14-AMoS2NR is anonmagnetic semiconductor with a band gap of 0.56 eV andthis is in good agreement with ref. 5. The band gap value isdetermined by the difference in the on-site energies of twoedges, and intra- and inter-edge hopping parameters of thetight-binding models.21 Because the clean 14-AMoS2NR is anonmagnetic semiconductor, 3d TMs (Mn, Fe, and Co) are usedas dopants to achieve magnetic properties. Seven substitutionsites are considered (Fig. 1(a)) with impurity concentrationscorresponding to 1.79 percent. Substituted by 3d TMs, the14-AMoS2NRs with their seven sites give seven configurations.

3d TM-doped 14-AMoS2NRs exhibit obvious configuration-dependent formation energies and electronic and magneticproperties. Their formation energies are calculated from

DHfðTMÞ ¼ EtotðTMÞ � EtotðcleanÞ �Xi

nimi; (1)

where Etot(TM) is the total energy of the doped 14-AMoS2NRand Etot(clean) is the total energy of the undoped 14-AMoS2NR.mi denotes the chemical potential of species i (host atoms ordopants), and ni the corresponding number of species that hasbeen added to or removed from the supercell.

For the 3d TM-doped 14-AMoS2NR, configuration 1 has thelowest formation energy (Fig. 1(c)), and hence is the mostfavored. Configuration 4 has the highest formation energy, sois the least favored. The 3d TM impurities tend to replace theoutermost cations. The order of the formation energies is Hf

(Mn)o Hf (Fe) oHf (Co). This can be attributed to size effects ofthe 3d dopants; the larger the atomic radius of the dopant, thecloser it is to the host Mo atom and thus the lower the formationenergy. From the configuration-dependent magnetic moment ofthe 3d TM impurities (Fig. 1(d)), the magnetic moments of theimpurities in configuration 1 for the 3d TM-impurity-doped14-AMoS2NRs are found to be larger than those of otherconfigurations. Mn, Fe, and Co impurities of configuration 1 havelocal magnetic moments of 3.3, 2.5, and 0.9 Bohr magnetons, (mB),respectively. Similarly, Mn, Fe, and Co adatoms on the MoS2

monolayer have local magnetic moments of 3.0, 2.0, and 1.0 mB,respectively.22

We further increase the concentration of 3d TM impuritiesto 3.57 percent to investigate the magnetic exchange interactions.For the configurations a and b of the optimized structures ofFe-impurity-pair-doped 14-AMoS2NRs (Fig. 2(a) and (b)), the Feimpurity pairs are the next-nearest-neighbors and nearest-neighbors along the edge. The total energy difference betweenthe ferromagnetic (FM) and antiferromagnetic (AFM) states isdefined as

DE = EAF � EF, (2)

where EAF and EFM are the total energies of the AFM and FMstate, respectively. DE is 21 meV for the Fe-impurity-pair-doped14-AMoS2NRs with configuration a, so the FM state is morestable than the AFM state. The magnetic exchange coupling ofconfiguration b gave a DE of 11 meV which is 10 meV smallerthan that of configuration a. There exists FM coupling betweenthe Fe impurity pairs. We further increased the on-site Coulombrepulsion interaction U to 5 and 6 eV and found that DE wasalmost unchanged. The Ruderman–Kittel–Kasuya–Yosida inter-action could be the origin of the ferromagnetism.23 The magneticexchange interactions between the 3d TM impurities in theHeisenberg model24 is written as:

H = �2JS1�S2, (3)

where J is the magnetic exchange coupling between neighboringmagnetic atoms; S1 and S2 are the spins of the magnetic atoms 1and 2 respectively. The total spin of the atom is given by S =(Nm � Nk)/2;25 here Nm and Nk are the number of spin-up and

Fig. 1 (a) Top view of the relaxed 14-AMoS2NR and its seven substitutionalsites. (b) SPDOS of relaxed 14-AMoS2NRs. (c) Formation energy of the 3dTM-doped 14-AMoS2NRs for the seven configurations. (d) Configuration-dependent magnetic moment (M) of the 3d TM impurities in 14-AMoS2NRs.14-AMoS2NRs are extended periodically along the y direction. Mo atoms areshown in blue, S atoms in orange, and Fe atoms in red. For S and Mo, theSPDOS presented here is the averaged value of each atomic species (thetotal SPDOS of S or Mo atoms divided by the number of atoms). This notionis used throughout the paper.

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spin-down electrons, respectively. According to eqn (2) and (3),the magnetic exchange coupling is obtained from J = DE/(4S1�S2).Here each Fe has a local magnetic moment of 2.5 mB. Thus, wecan take S = S1 = S2 = 1.25. Based on these values, the magneticexchange coupling J is 3.36 meV for Fe-doped 14-AMoS2NR withconfiguration a. The Curie temperature TC as estimated usingthe mean field method26 is

TC ¼2SðS þ 1Þ

3kBJ ¼

1þ 1

S

� �DE

6kB; (4)

Here the calculated TC is 73 K. From the magnetic exchangecoupling for Fe-pair-doped AMoS2NRs of different widths (seeTable 1), it is found that DE is 30, 15, and 22 meV for theFe-doped 10-, 12- and 16-AMoS2NRs, respectively, in configurationa giving a corresponding TC of 104, 52, and 76 K calculated usingeqn (4). DE is 10, 8, and 13 meV for the Fe-doped 10-, 12-, and

16-AMoS2NRs, respectively, in configuration b giving a corre-sponding TC of 35, 28, and 45 K. For these AMoS2NRs, the TC

associated with configuration a is higher than that of configu-ration b. As indicated in Fig. 2(c), the magnetization of a doped14-AMoS2NR is mainly distributed on the Fe pair, and the Mo atomsalong the doped edge have opposite magnetization directions to Fe.The edge states contribute mainly to the magnetization and occupythe electronic orbitals near the Fermi level. Thus the edge statesare more active and dominate the physical properties ofAMoS2NRs. Compared with clean 14-AMoS2NRs, the band gapof the Fe-pair-doped 14-AMoS2NR has been obviously reduced.From Fig. 2(d), the band-gap values are found to be 0.35 and0.29 eV for the spin-up (majority) and spin-down (minority)bands, respectively. The blue shifts of the band gaps of 3dTM-doped AMoS2NRs are expected to be observed in experiments.Similar band gap reduction effects were found in Cu-dopedZnO.27 Hybridization of the Fe-impurity bands with MoS2 raisesup the valence band of the 14-AMoS2NRs, which leads to areduction in the band gap. Moreover, Fe (3d64s2) has morevalence electrons than Mo (4d55s1), so it could inject excesselectron carriers into MoS2 and lead to N-type doping effects.Similarly, doping of the Co (3d74s2) and Mn (3d54s2) impuritieswill also turn MoS2 into a N-type semiconductor. This isconfirmed from results obtained from density function theorycalculations indicating that the Fermi level is raised by thedoping of these 3d TM impurities. For doped 14-AMoS2NRs,substitution of Mn, Fe, and Co with a concentration of 3.57percent will lift up the Fermi level by 0.09, 0.01, and 0.20 eV,respectively. This will enhance the local chemical affinity andreduce the work function of AMoS2NRs.

Similarly, given the magnetic exchange couplings for the Mn andCo impurities in AMoS2NRs (see Table 1), the values of all DE arenegative, so the AFM state should be the ground state for Mn- andCo-doped AMoS2NRs. The impurity concentration in 14-AMoS2NRsis further increased to 7.14 percent (all Mo atoms of the left edge aresubstituted by Fe). The magnetization of this configuration (Fig. 2(e))is mainly distributed on the Fe impurities, with the Mo atoms alongthe doped edge having opposite magnetization directions to Fe. DEwas 278 meV for two Fe impurity pairs, so we should normalize thevalue of DE to 139 meV. The magnetic exchange coupling J is 22 meVas calculated by J = DE/(4S1�S2) and the TC is 481 K as calculated fromeqn (4). Thus the magnetic exchange coupling is enhancedby increasing the concentration of Fe impurities; the TC of theFe-doped 14-AMoS2NR is far above room temperature.

Based on the SPDOS (Fig. 2(f)), the band gap of spin-up andspin-down bands is 0.18 and 0.26 eV, respectively, so the bandgap has been further reduced by increasing the concentrationof Fe impurities.

Fig. 2 Top views of the Fe-impurity-pair-doped 14-AMoS2NR with con-figurations (a) a and (b) b. (c) 0.04 e �3 isosurface and (d) SPDOS of the FMstate of configuration a. (e) 0.04 e �3 isosurface and (f) SPDOS of the FMstate of the Fe-doped 14-AMoS2NR with a higher impurity concentrationof 7.14 percent. For isosurfaces of the magnetization density distribution,white corresponds to a positive magnetization isosurface, and purplecorresponds to a negative magnetization isosurface. This notion is usedthroughout the paper.

Table 1 Summary of DE (meV) for 3d TM impurity-doped AMoS2NRs ofdifferent widths. a and b refer to configurations a and b, respectively

10_a 10_b 12_a 12_b 14_a 14_b 16_a 16_b

Mn �26 �13 �20 �16 �23 �14 �23 �18Fe 30 10 15 8 21 11 22 13Co �4 �3 �3 �5 �5 �7 �6 �5

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The temperature-dependent magnetic moment can be esti-mated from the Stoner and spin-fluctuation models,26

M ¼M0 1� T

TC

� �2" #12

; (5)

M ¼M0 1� T

TC

� �� �12; (6)

where M0 is the magnetization of the ground state. M0 of eachFe impurity of a doped 14-AMoS2NR, with structure shown inFig. 2(e), is 2.5 mB. As the temperature increases, M decreases. Atroom temperature (300 K), the Stoner and spin-fluctuation modelspredict 1.9 and 1.5 mB, respectively, for M. The Fe impurity still has astrong magnetic moment at room temperature because of the highTC. This is very important for MoS2 applications in spintronics andmagnetic data storage.

The electronic and magnetic properties of zigzag MoS2

nanoribbons (ZMoS2NRs) doped with 3d TMs were also inves-tigated. The relaxed structure of a clean 10-ZMoS2NR is shownin Fig. 3(a). From the SPDOS (Fig. 3(b)), it is found that the10-ZMoS2NR shows spontaneous magnetization. The Mo 4dshows strong spin-polarization whereas the S 3sp is weaklyspin-polarized. The band gap of both majority and minoritybands is zero. Thus the 10-ZMoS2NR is a metallic magnet. Eachoutermost Mo has the strongest magnetization, with a localmagnetic moment of 0.7 mB whereas each outermost S has alocal magnetic moment of 0.3 mB. The magnetization is mainlylocalized on the edges of the 10-ZMoS2NR (see Fig. 3(c) and (d)).

3d TM impurities are used to dope the 10-ZMoS2NR to modulatethe electronic and magnetic properties. Ten substitutional sites ofthe 3d TM dopant with a concentration of 2.5 percent areconsidered for the 10-ZMoS2NR (Fig. 3(a)). The width of therelaxed 10-ZMoS2NR is around 2.6 nm. The stabilities of theconfigurations are analyzed by comparing the formation energiesof different configurations (see Fig. 3(e)). For Mn-, Fe-, andCo-doped 10-ZMoS2NRs, configuration 10 has the lowest formationenergy because the bonds between the impurities and host atomscan be fully relaxed at the edges. Configuration 1 has the secondlowest formation energy. Configuration 6 has the largest formationenergy because the relaxation of the bonds between impurities andhost atoms is restricted. This can be interpreted as an edge effect inwhich the formation energy is lower when the impurities are nearerthe edge. This is in agreement with experimental scanning trans-mission electron microscopic (STEM) findings that Co impuritiesreplace the cations at the Mo edges of MoS2 nanowires.11 Althoughthere are rarely experimental reports on the substitutionalbehaviors of Mn and Fe of Mo in MoS2, from a thermodynamicpoint of view, we predict that Mn and Fe will also replace thecations at the Mo edges of MoS2.

From Fig. 3(f), we can observe that the 3d TM impurities ofconfiguration 10 have the largest magnetic moment with Mn, Fe,and Co having local magnetic moments of 3.3, 2.4, and 1.0 mB,respectively. Similarly, Mn, Fe, and Co adatoms on the MoS2

monolayer have local magnetic moments of 3.0, 2.0, and 1.0 mB,respectively.22 Impurities of the 3d TM-doped 10-ZMoS2NRs exhibitobvious configuration-dependent magnetic properties. The nearerthe impurities are to the edge, the larger the magnetic moments are.

To investigate the magnetic exchange coupling betweenimpurities, we increased the dopant concentration to 5 percents.For the calculated structures of 10-ZMoS2NRs doped withCo-impurity pairs (Fig. 4(a) and (b)), the total energy of configu-ration g is 0.16 eV smaller than that of configuration d; thusconfiguration g is more stable than configuration d. Co impuritiesare distributed uniformly at the Mo edge. For Mn- and Fe-doped10-ZMoS2NRs, the total energy of configuration g is, respectively,0.11 and 0.03 eV smaller than that of configuration d, and henceMn and Fe are also distributed uniformly at the Mo edge. ForCo-doped 10-ZMoS2NRs with configuration g, there is strongstructural reconstruction at the Mo edge (Fig. 4(a)). Co atoms arerelaxed towards interior sites of 10-ZMoS2NRs and form bonds withthe neighboring Mo atoms, and thereby stabilize this configurationg. From experimental STEM images, we can say that configurationg appears for Co-doped WS2 nanowires.11

From Table 2, DE is found to be 68 and 71 meV for theconfigurations g and d, respectively, of Co-doped 10-ZMoS2NRs.Each Co impurity has a magnetic moment of 1.0 mB; thus wecan take S = S1 = S2 = 0.5 here. According to J = DE/(4S1�S2), themagnetic exchange coupling is 69 and 71 meV for configura-tions g and d, respectively. The corresponding TC is 398 and410 K as calculated by eqn (4). Thus Co-doped 10-ZMoS2NRmanifests a strong FM nature with TC above room temperature.The magnetization distribution of Co-doped 10-ZMoS2NRs withconfiguration g is displayed in Fig. 4(c) which shows that themagnetization is mainly distributed on the edgiest S and Co

Fig. 3 (a) Top view of the geometric structure of the relaxed 10-ZMoS2NRand its ten substitutional sites. (b) SPDOS of the 10-ZMoS2NR. (c) Top and(d) side views of the 0.02 e �3 isosurface of the magnetization densitydistribution of the 10-ZMoS2NR. Configuration-dependent (e) formationenergy and (f) M of 3d TM impurities of doped 10-ZMoS2NRs.

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atoms. Each edgiest S has a local magnetic moment of 0.4 mB,which is 0.1 mB larger than that of the clean 10-ZMoS2NR. Thusdoping the right Mo edge with Co impurities could also influencethe magnetic properties of the left S edge of the 10-ZMoS2NR. Thesetwo edges contribute mainly to the states near the Fermi level anddominate the physical properties of 10-ZMoS2NRs.

The DOS of the FM state for the Co-doped 10-ZMoS2NR withconfiguration g (Fig. 4(d)) shows that the Co impurities exhibitstrong spin-polarization. For both spin-up and spin-down bands,the electrons occupy the Fermi-level states. The Co-doped10-ZMoS2NR is still metallic, but the DOS distribution near theFermi level has been strongly tuned by impurities in contrast tothe clean 10-ZMoS2NR. The temperature-dependent magneticmoment of the Co-doped 10-ZMoS2NR (Fig. 4(e)) shows that asthe temperature increases, the magnetic moment decreases. Atroom temperature, the magnetic moment of the Co-impurity is0.5 and 0.7 mB, as predicted by spin-fluctuation and Stonermodels, respectively. From Table 2, DE is found to be positivefor Co-doped 6-, 8-, and 12-ZMoS2NRs, so these ZMoS2NRs alsopossess an FM ground state. According to eqn (4), the TCs ofthese Co-doped ZMoS2NRs are also above room temperature.

Also from Table 2, it is found that Mn-doped ZMoS2NRsexhibit configuration-dependent magnetic properties. Configurationg is FM, whereas configuration d is AFM. For the Mn-doped

10-ZMoS2NR, we can take S = S1 = S2 = 1.65, because each Mnhas a local magnetic moment of 3.3 mB. In accordance withJ = DE/(4S1�S2), the magnetic exchange coupling is 10.9 and�7.3 meV for configurations g and d, respectively. The TC is355 K for configuration g as calculated by eqn (4). For Mn-dopedZMoS2NRs, configuration d exhibits AFM characteristics due tothe superexchange interaction between the nearest-neighbor Mnatoms, while in configuration g the impurities are remote.Similar effects were also found for Mn doped ZnO with impuritiesin the nearest-neighboring configuration.28,29

All Fe-doped ZMoS2NRs exhibit FM characteristics. RegardingFe-doped 10-ZMoS2NRs, we can take S = S1 = S2 = 1.2 here as each Fehas a local magnetic moment of 2.4 mB. From J = DE/(4S1�S2), themagnetic exchange coupling is found to be 4.5 and 8.3 meV forconfigurations g and d, respectively, with the corresponding TC of91 and 169 K. Again, the TCs are well below room temperature, thusFe-doped 10-ZMoS2NRs manifest weak FM characteristics. AlthoughZMoS2NRs are naturally magnetic, incorporating 3d TM impuritiescould further tune their magnetic and electronic properties.

Conclusions

In summary, the electronic and magnetic properties of MoS2

nanoribbons can be tuned with 3d TM impurities. Theseimpurities tend to substitute the edgiest cations of AMoS2NRs andZMoS2NRs. Fe-doped AMoS2NRs manifest a FM semiconductingnature and their TC can be tuned by adding impurities. In contrast,Co and Mn-doped AMoS2NRs are AFM semiconductors. Co-dopedZMoS2NRs show metallic and strong FM characteristics with TC

above room temperature. Mn-doped ZMoS2NRs show configuration-dependent magnetic properties. Fe-doped ZMoS2NRs are weak FMsemiconductors. Our results provide an insight at the atomic level ofthe electronic and magnetic properties of 3d TM-doped MoS2

nanoribbons and pave the way for future applications of MoS2 andother transition metal dichalcogenides in nanoelectronic and spin-tronic devices.

Acknowledgements

The authors gratefully acknowledge financial support from NationalNatural Science Foundation of China (No. 11304206 and 21001051),National Natural Science Foundation of Shenzhen University (No.827000001 and 82700002601), Strategic Emerging Industry Develop-ment Special Fund of Shenzhen (JCYJ20130326111743703 andJC201105170651A), Shenzhen Key Laboratory of Sensor TechnologyOpen Project (SST201302) and Shenzhen Key Laboratory of SpecialFunctional Materials Open Project (T201303). The authors would liketo thank the National Supercomputing Center in Shenzhen and theHigh Performance Computing Center of Shenzhen University for thecomputational facilities.

Notes and references

1 K. F. Mak, C. Lee, J. Hone, J. Shan and T. F. Heinz, Phys. Rev.Lett., 2010, 105, 136805.

Fig. 4 Top views of Co-impurity-pair-doped 10-ZMoS2NRs with config-urations (a) g and (b) d. (c) 0.02 e �3 isosurface and (d) SPDOS of the FMstate of configuration g. (e) Temperature-dependent M of Co impurity inthe doped 10-ZMoS2NR with configuration g.

Table 2 Summary of DE (meV) for 3d TM impurity-doped ZMoS2NRs withdifferent widths. g and d indicate the configurations g and d, respectively

6_g 6_d 8_g 8_d 10_g 10_d 12_g 12_d

Mn 76 �86 103 �88 115 �79 107 �83Fe 30 28 32 35 26 48 23 51Co 74 66 78 70 69 71 73 75

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