Interface Magnetism in Vanadium-doped MoS$_2$/Graphene Heterostructures

TL;DR

This work demonstrates that magnetism in two-dimensional Graphene/MoS2 heterostructures can be tunably induced and enhanced by Vanadium doping and defect engineering, as shown by first-principles DFT calculations and corroborated by VSM experiments. The study reveals that dopant concentration and defect type dictate magnetic moments and interfacial ferromagnetism, with notable interlayer charge transfer from Graphene to the MoS2 layer and defect-localized states shaping the electronic and magnetic landscape. Importantly, Graphene's presence can both suppress and amplify magnetism depending on defect configurations, and experimental results show a substantial interfacial enhancement of saturation magnetization at room temperature, consistent with the proposed microscopic mechanisms. Overall, the findings provide a concrete framework for defect- and doping-engineered magnetism in TMDC/Graphene heterostructures, offering a pathway toward targeted spintronic functionality in 2D materials.

Abstract

Magnetism in two-dimensional materials is of great importance in discovering new physical phenomena and developing new devices at the nanoscale. In this paper, first-principles simulations are used to calculate the electronic and magnetic properties of heterostructures composed of Graphene and MoS$_2$ considering the influence of point defects and Vanadium doping. It is found that the concentration of the dopants and the types of defects can result in induced magnetic moments leading to ferromagnetically polarized systems with sharp interfaces. This provides a framework for interpreting the experimental observations of enhanced ferromagnetism in both MoS$_2$/Graphene and V-doped MoS$_2$/Graphene heterostructures. The computed electronic and spin polarizations give a microscopic understanding of the origin of ferromagnetism in these systems and illustrate how doping and defect engineering can lead to targeted property tunability. Our work has demonstrated that through defects engineering, ferromagnetism can be achieved in V-doped MoS$_2$/Graphene heterostructures, providing a potential way to induce magnetization in other TMDC/Graphene materials and opening new opportunities for their applications in nano-spintronics.

Figures (8)

• Figure 1: (a) Side view of the pristine HST showing labels for the different atoms and the interlayer separation $d$. Top views of the Gr monolayers as part of the V-doped MoS2/Gr HSTs: (b) pristine Gr, (c) Gr+V_C (with C monovacancy). Top and side views of the various V_0.02Mo_0.98S2 monolayers as part of the V-doped MoS2/Gr HSTs: (d) V_0.02Mo_0.98S2 (with $2\%$ V substitutional doping), (e) V_0.02Mo_0.98S2+V_S (with $2\%$ V substitutional doping and S monovacancy), (f) V_0.02Mo_0.98S2+V_S-S (with $2\%$ V doping and S divacancies on the same atomic layer), (g) V_0.02Mo_0.98S2+V_2S (with $2\%$ V substitutional doping and S divacancies on different atomic layers), (h) V_0.02Mo_0.98S2+V_Mo (with $2\%$ substitutional V doping and Mo monovacancy), (i) V_0.02Mo_0.98S2+V_Mo+2S (with $2\%$ V doping and an Mo+2S defect complex).
• Figure 2: Interlayer binding energy $E_b$ (eV) as a function of the interlayer separation $d$ (Å) of HSTs: (a) Gr/TMDCs and (b) (Gr+V_C)/TMDCs.
• Figure 3: Total magnetization of the: (a) entire HST $M_{tot}$$(\mu_B)$, (b) Gr layer $M_{Gr}$$(\mu_B)$, (c) TMDC layer $M_{TMDC}$$(\mu_B)$ as part of HSTs. The data is given as a function of the different TMDC used to construct each HST.
• Figure 4: Electron spin densities of: (a) Gr/$\ch{V_{0.02}Mo_{0.98}S2}$, (b) Gr/V_0.04Mo_0.96S2, (c) Gr/(V_0.02Mo_0.98S2+V_S-S), (d) Gr/(V_0.02Mo_0.98S2+V_Mo+2S), (e) (Gr+V_C)/V_0.02Mo_0.98S2, (f) (Gr+V_C)/V_0.04Mo_0.96S2, (g) (Gr+V_C)/(V_0.02Mo_0.98S2+V_S-S) and (h) (Gr+V_C)/(V_0.02Mo_0.98S2+V_Mo+2S) HSTs. Green and blue colors represent the spin-up and spin-down charges, respectively. The pink circles represent S vacancy positions. The isosurface value is $10^{-3}$$e$/Å$^3$).
• Figure 5: Band structures of (a) Gr/MoS2, (b) Gr/V_0.02Mo_0.98S2, (c) Gr/V_0.04Mo_0.96S2 and (d) Gr/(V_0.02Mo_0.98S2+V_Mo+2S) HSTs where the dotted lines represent the Fermi level.