Computational Modeling and Design of Magnetic Properties in 2D Cr-, Mn-, and V- Based Nanostructures for Spintronic Applications

Abstract

The emergence of two-dimensional (2D) magnetism presents transformative opportunities for the development of next generation magnetoelectric nanodevices. These materials, characterized by their ultrathin, flexible and novel properties, enable magnetic functionalities previously unattainable in conventional three-dimensional materials. Such advances have profound implications for data storage, quantum computing, and sensing technologies, offering superior performance and miniaturisation. The precise manipulation of magnetism at the atomic level unlocks unique design possibilities and paves the way for innovative device architectures. Exploration of the exceptional magnetic and electronic properties of two-dimensional (2D) materials has opened new horizons for advanced spintronic and valleytronic applications. Using first- principles calculations this work investigates three key strategies for the enhancement of 2D magnetism. The first strategy is hydrogenation. The discovery of two-dimensional (2D) magnetism has opened exciting opportunities for the development of next generation magnetoelectric nanodevices. However, the widespread application of such materials is currently limited by the scarcity of systems that simultaneously exhibit large magnetic anisotropy and high transition temperatures. Tailoring the magnetic properties of existing 2D materials to address this challenge has become a subject of intense research. In this work, we explore the effects of hydrogenation on the magnetic and electronic properties of the recently synthesised CrSe₂ monolayer using first-principles calculations. The CrSe₂ monolayer demonstrates excellent dynamical and thermal stability at lower degrees of hydrogenation, with its magnetic ground state transitioning from antiferromagnetic (AFM) to ferromagnetic (FM) upon hydrogen adsorption. Notably, the magnetic anisotropy energy (MAE) of the CrSe₂ monolayer increases significantly from 0.32 meV/Cr to 0.68 meV/Cr after hydrogenation, and this is accompanied by an enhancement 3 of its Curie temperature. This improvement is attributed to inter-atomic charge redistribution induced by hydrogen adsorption. These results highlight hydrogenation as an effective and non-volatile strategy for enhancing 2D magnetic coupling, offering promising prospects for advanced spintronic applications. Next, we investigate the effects of atomic intercalation on the magnetic and electronic properties of the CrSe₂ bilayer using first-principles calculations. Our results demonstrate that the intercalation significantly impacts the magnetic properties while maintaining excellent thermal stability. The magnetic ground state of the CrSe₂ bilayer possesses an AFM- FM transition for most intercalated atoms. The Na and Be intercalations in particular exhibit unique behaviour. The intercalation with Be atoms leads to a dramatic increase in the magnetic anisotropy energy (MAE) from 0.16 meV/Cr in the pristine bilayer to 0.82 meV/Cr in the CrSe₂-Be bilayer. The transition temperature also rises from 75 K in the pure bilayer to 300 K for the CrSe₂-Be system. Interestingly, CrSe₂-Be exhibits an A-type AFM order. This significant enhancement in magnetic properties is attributed to the redistribution of interatomic charge induced by intercalation. These findings highlight atomic intercalation as a powerful strategy for improving long-range 2D magnetic coupling. Lastly, we design a van der Waals (vdW) heterostructure between AFM MnPS3 and FM VTe2 monolayers and explore its magnetic and electronic behaviour. Six stacking configurations were constructed in the attempt to realise the most stable structure. As a result, the Mn-Te, P-Te, and S-Te stackings were found to be the most thermodynamically stable, as evidenced by their low binding energies. Among these, the Mn-Te stacking demonstrates remarkable properties, including strong perpendicular magnetic anisotropy (PMA) with a MAE reaching 7.32 meV/V, which is double that of the individual monolayers. Thus, the large and tunable perpendicular magnetic anisotropy (PMA) is caused by an 4 antiferromagnetic (AFM) monolayer. According to the detailed charge analysis using Bader charge calculations and charge density difference the Mn-Te stacking exhibits charge loss of around -0.483(e/Mn) and -0.303 (e/S) so acting as a primary charge donor, which directly correlates with its enhanced PMA. Furthermore, electronic structure analysis shows that the MnPS₃/VTe₂ heterostructure exhibits a half-metallicity in the Mn-Te stacking. These findings highlight the MnPS₃/VTe₂ heterostructure as a robust platform for spintronic applications, and they offer valuable insights into interfacial interactions and mechanisms for enhancing magnetic anisotropy in 2D heterostructures. This work underscores the potential of tailored vdW heterostructures to drive further advances in 2D spintronic technologies.