Anab initiostudy of transition metals doped with WSe₂for long-range room temperature ferromagnetism in two-dimensional transition metal dichalcogenide

Abstract

We report a systematic study of the magnetic properties in transition metals doped with WSe2 through the use of first principle calculations. The results demonstrate the possibility of generating long-range room temperature ferromagnetic interaction in WSe2 with the use of Mn and Fe doping. In the case of Fe, a percolation threshold is required for long-range ferromagnetism, whereas the long-range room temperature ferromagnetic interaction in Mn-doped WSe2 persists even at a low concentration (~5.6%). The ferromagnetism is mediated by the delocalized p states in the Se atoms, which couple antiferromagnetically with the spin-down a1 and e1 states in Fe doping through a correlated interaction. In Mn doping, the p states of Se tend to couple ferromagnetically with the 3d state of Mn, which stabilizes the long-range ferromagnetism between the Mn ions, although the short-range interaction is antiferromagnetic. In addition, the calculations indicate that Fe and Mn tend to configure at a high spin state, thus they possess much larger magnetic moments in WSe2 than when they are doped into other transition metal dichalcogenides. We also discovered a strong dependence of the exchange interaction on the dopants' spatial positions, distances, and concentrations, which alters the magnetic coupling from strong ferromagnetism to strong antiferromagnetism. These results can provide useful guidance to engineer the magnetic properties of WSe2 in future experiments.

Strain-controlled switch between ferromagnetism and antiferromagnetism in1T−CrX2(X=Se, Te) monolayers

“…However, neither graphene nor most of the TMDs monolayers is intrinsically magnetic. Many methods can be used to induce the magnetic properties in the TMDs monolayers, mainly including doping, [7][8][9][10] hydrogenation, [11][12][13][14] and forming zigzag edges. 15,16 In the nanoelectronic applications, however, we expect the magnetism can be precisely and flexibly controlled.…”

DFT study of itinerant ferromagnetism in p -doped monolayers of MoS2

“…A number of intrinsic defects have been found to form local moments [27][28][29][30][31] in MX 2 materials and suggestions have been made to make the MX 2 materials magnetic by adsorption of impurity atoms, 27,28,32,33 or by substituting M or X atoms with impurity atoms. 28,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] Even though the Mermin-Wagner theorem 7,8 tells us that there is no long range ordering in two dimensions for isotropic Heisenberg exchange, few attempts have been made to determine the exchange coupling between magnetic impurities 33,37,38,40,41,47,51 and it was only very recently that the magnetic anistropy of a defect was calculated, for an antisite defect in MoS 2 . 31 Replacing some of the M atoms with Hund's-rule coupled transition metal atoms like Mn or Fe gives rise to deep impurity levels in the semiconductor gap.…”

“…Where attempts have been made to estimate the Curie temperature, the predicted values are either very low or the concentration of transition metal dopant is so high that the doped material is no longer a semiconductor. 35,37,38,40,41,50 Based upon the electronic structure shown in Fig. 1(b), we explore a different approach to making MoS 2 ferromagnetic in this manuscript.…”

Electronic structures and magnetic properties in Cu-doped two-dimensional dichalcogenides

“…Theoretical works have reported that diverse magnetic orderings can be realized in transition-metal-doped MX2 [11][12][13][14][15][16][17][18][19]. Based on density functional theory, Feng et al have shown that Fe-terminated Fe4N in contact with monolayer MoS2 has potential in spintronics devices, [20] and Zhang et al have predicted that the contact between monolayer MoS2 and Gd(0001) can be used to realize good spin injection [21].…”