Controlling interlayer magnetic coupling in the two-dimensional magnet Fe3GeTe2

Interlayer magnetic coupling in emerging two-dimensional layered magnets holds great potential for manipulating layered magnetic structures for cross-layer transport or tunneling phenomena. In this paper, we employed first-principles calculations to show enhanced ferromagnetic (FM) interlayer exchange coupling for ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ by reducing stacking symmetry or reducing the layer number. Electronic structure analysis reveals that the former is mainly due to low-symmetry enhanced interlayer orbital hopping, and the latter originates from reduced Pauli potential for out-of-plane metallic electrons with respect to thicker layers. Interlayer FM coupling could also be weakened by substrates due to the screened Coulomb interactions, simulated by reducing the onsite Coulomb repulsion for Fe $d$ electrons. In this paper, we provide guidance to rationally control interlayer magnetic coupling via engineering stacking configuration and dielectric environment.