Intercalation induced ferromagnetism in group-V transition metal dichalcogenide bilayer

H M R Ahamd,Jian Zhou

doi:10.1063/1.5139061

Abstract

Two-dimensional (2D) ferromagnetic materials are receiving great attention in recent years. However, owing to strong direct magnetic coupling between different layers, they usually prefer antiferromagnetic coupling between different layers once stacked together. It would be of great interest if one can tune such antiferromagnetism to ferromagnetism, which is preferable for further magnetic information storage, and large magnetic moments can be achieved (proportional to thin-film thickness). In the current work, we theoretically and computationally suggest an effective method to tune the interlayer magnetic coupling between two magnetic materials (VX2, X = S, and Se). We show that intercalating a layer of alkali metals could enhance indirect magnetic exchange, and ferromagnetic interlayer coupling between different VX2 layers can be achieved. Our work provides a new and effective route to control and modulate the magnetic exchange between 2D magnetic materials.

Highlights

Another interesting ferromagnetic (FM) material that has been recently discovered is group-V transition metal dichalcogenide (TMD) monolayer with a high Curie temperature.10 Compared with group-VI TMD monolayers, which are nonmagnetic,14 the transition metals in group-V TMD are in their nd1 (n = 3 or 4) electronic character
By calculating different magnetic coupling orders, we show that the VX2 bilayer would prefer ferromagnetic coupling once intercalated by large sized alkali metals (AMs) with a high concentration
We find that when two layers of VX2 are stacked together (Fig. 1), they leave a van der Waals gap of ∼3.7 Å

Summary

Introduction

Compared with group-VI TMD monolayers (such as MoS2 and its analogous structures), which are nonmagnetic, the transition metals in group-V TMD are in their nd (n = 3 or 4) electronic character This unpaired electron makes the VSe2 monolayer become spin-polarized, and the coupling between different V atoms prefers to be FM. Larger valley degeneracy splitting with a time-reversal symmetry broken is predicted in heavier elements with strong valley polarized plasmonic behavior.27 With these promising properties of ferromagnetic groupV TMD monolayers, when two layers are stacked scitation.org/journal/adv together, the interlayer magnetic exchange shows antiferromagnetic (AFM) coupling with zero net magnetic moments. Reshak and Auluck performed linear augmented planewave calculations on AMs intercalating layered VSe2 and observed hybridization between AM-s,p states with V-d and Se-p orbitals, consistent with the previous argument.37 In these studies, they performed spin-unpolarized calculations on bulk materials Reshak and Auluck performed linear augmented planewave calculations on AMs intercalating layered VSe2 and observed hybridization between AM-s,p states with V-d and Se-p orbitals, consistent with the previous argument. in these studies, they performed spin-unpolarized calculations on bulk materials

Methods

Results

Conclusion