Electric-field induced half-metallicity in a two-dimensional ferromagnetic Janus VSSe bilayer

Abstract

Two-dimensional (2D) half-metals with intrinsic ferromagnetism hold great potential for applications in spintronics. In this study, we aim to expand the known space of such 2D ferromagnetic (FM) half-metals by investigating bilayer of Janus VSSe, an FM semiconductor. Its structural, electronic, and magnetic properties are examined using density functional theory, employing the DFT+$U$ method, coupled with the PBE functional. The stability of the bilayer is examined using ab initio molecular dynamics simulations at finite temperatures up to 400 K. To ensure the stability further, the elastic constants of the system have also been investigated and we found that VSSe bilayer manifests an easy plane of magnetization similar to its monolayer counterpart. At the DFT+$U$ level, the considered VSSe bilayer exhibits a tendency towards half-metallicity with a small band gap of 0.11 eV for the majority spin carriers, and of 0.66 eV for the minority ones. To include a transition from a semiconductor to a half-metal, the bilayer is subjected to an external electric field of varying strengths normal to the plane. The lack of horizontal mirror symmetry in the bilayer allows bidirectional tuning of the band gap, with different values for the field in "upward" and "downward" directions. The band gaps for the two spin channels increase with the increasing upward electric field, while the opposite happens for the downward fields, with the majority carrier gap closing at 0.16 V/$\unicode{x212B}$, making the material a spin gapless semiconductor. Further increase in the electric field renders the material half metallic at 0.18 V/$\unicode{x212B}$. Given the fact that these values of the external electric field are achievable in the lab suggests that the FM Janus VSSe bilayer is a promising candidate for spintronic devices.

41 pages, 13 figures in the Manuscript and 8 figures in the Supplemental Material

References in corpus (15)

• VASPKIT: A User-friendly Interface Facilitating High-throughput Computing and Analysis Using VASP Code
• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• Room Temperature Intrinsic Ferromagnetism in Epitaxial Manganese Selenide Films in the Monolayer Limit
• Calculations of Hubbard U from first-principles
• Two dimensional magnets: Forgotten history and recent progress towards spintronic applications
• Unique gap structure and symmetry of the charge density wave in single-layer VSe${}_2$
• The electronic structure and elastic property of monolayer and bilayer transition metal dichalcogenides MX${}_2$ (M=Mo,W;X=O,S,Se,Te): A comparative first-principles study
• Generating extreme electric fields in 2D materials by dual ionic gating
• Two-dimensional fully-compensated Ferrimagnetism
• Quantum size effects in layered VX2 (X=S, Se, Te) materials: Manifestation of metal to semimetal or semiconductor transition
• Spin gapless semiconductors
• Structural, electronic, and magnetic properties of Vanadium-based Janus dichalcogenide monolayers: A first-principles study
• Fragile Symmetry-Protected Half Metallicity in Two-Dimensional van der Waals Magnets: A Case Study of Monolayer FeCl2
• Novel 2D vanadium sulphides: synthesis, atomic structure engineering and charge density waves