Enhancing the magnetic properties (Curie temperature and magnetic anisotropy energy) of a 2D MXene (Ca2C) by stacking a vdW heterostructure with silicene

Abstract

First-principles calculations within spin polarized density functional theory (SP-DFT) were used to study the stability, and the electronic and magnetic properties of a vdW heterostructure by stacking an MXene (Ca₂C) and silicene, forming the Ca₂C/silicene van der Waals (vdW) heterostructure. Our results show that the Ca₂C/silicene presents structural integrity without deformations, being a ferromagnetic metal system. The small magnetic moment (0.087µ_B) in the pristine Ca₂C layer, which is mainly localized in the p-planar orbitals of the C atom, increases to 0.64µ_B in the Ca₂C/silicene heterostructure due to the asymmetry in the spin of the π electrons that flow from MXene to silicene. Furthermore, the Curie temperature in the Ca₂C/silicene heterostructure is strongly enhanced (T_C = 340 K) and calculations of the magnetic anisotropy energy (MAE) show that it is double when the vdW heterostructure forms. Furthermore, the easy magnetization axis changes from the planar (Ca₂C monolayer) to the perpendicular direction (vdW heterostructure). The high T_C and MAE open a channel for the construction of magnetic devices using light atoms (without the presence of d and/or f electrons). In addition, the electronic and magnetic properties of the vdW heterostructure can be tailored by vertical strain.