Room-temperature ferromagnetism in Co doped MoS₂ sheets

Abstract

Via the hydrothermal method, we synthesized MoS2 nanosheets with varying Co dopant concentrations of 0%, 3%, 7%, using cobaltous acetate as a promoter, and marked as A, B, and C, respectively. We found that the thickness and flatness of the nanosheets increased with the increase of the Co dopant concentrations. Meanwhile, the BET surface area of samples (A, B, and C) decreased with the increase of the Co dopant concentrations. Optical absorption spectroscopy showed that, compared to sample A, the A1 and B1 excitons of samples B and C were 10 and 23 meV redshifted, respectively. Then, we performed magnetization measurement to investigate the effect of Co-doping; the unique result implied that the values of the magnetic moment decreased with the increase of the Co dopant concentrations. We performed DFT computations to address the above magnetic result. The computational result indicated that the value of the magnetic moment decreased with the increase of the Co dopant concentrations, which is in agreement with the results of the experiments described above.

High Coercivity and Magnetization in WSe2 by Codoping Co and Nb

“…Initially, XRD peaks from the substrate with double‐tape are measured without the sample and same are labeled with a dark yellow sphere in Figure a. 4Co, 1Nb‐4Co, 2Nb‐4Co, and 5Nb‐4Co samples show prominent XRD peaks which are evidence of good crystalline structures . To further analyze the doping effects on crystalline structural properties, the strongest peak of (008) plane is magnified, as shown in Figure b.…”

“…good crystalline structures. [32] To further analyze the doping effects on crystalline structural properties, the strongest peak of (008) plane is magnified, as shown in Figure 2b. After 4 at% Co doping in WSe 2 , (008) peak marginally shifts to a higher diffraction angle.…”

“…The nonexistence of Co and Nb related peak further bolsters our claim of effective substitutional doping. Figure 2a,b shows the hexagonal structure of WSe 2 (Database: PDF 4+ & ICSD with Findit) from X-ray diffraction (XRD) analysis, [32] which remains unaffected after doping (Co and Nb). For XRD measurements, samples were mounted on the Al 2 O 3 substrate with the help of a tiny piece of double-tape.…”

Effects of strain on electronic and magnetic properties of Co/WS2 nanolayer: A density functional and Monte Carlo study

“…Experimental observations confirm occurrence of ferromagnetism in the similar Co/WSe 2 and Co/MoS 2 junctions. 5,18 The observed FM ground state of the Co/WS 2 junction is likely due to the superexchange interaction between neighboring cobalt atoms in the Co monolayer, because of the rather large distance (∼ 3.18Å) between these Co atoms. On the other hand, the close Co-S distance of about 2.11Å shows that S atoms are able to mediate a superexchange interaction between cobalt atoms.…”

Electron Spin Dynamics of Two‐Dimensional Layered Materials

“…Cheng et al demonstrated that several transition metals can be incorporated to WS 2 nanoflakes, and while their doping with Gd 3+ was employed for magnetic resonance imaging, one could easily envision translating such materials into spintronic applications. The synthesis of Co‐doped MoS 2 nanosheets can also be synthesized hydrothermal methods with cobalt atoms incorporated at edge sites . The doped samples exhibited room‐temperature ferromagnetism, however the authors noted that the total magnetic moment was observed to reduce due to morphological changes while varying Co concentration …”