Manipulating magnetic coupling and magnetic anisotropy in bilayer FeBr2 via stacking order and interlayer distance

Motivated by the recent experimental fabrication of few-layer FeBr2, we systematically investigate the effects of stacking order and interlayer distance on the magnetic and electronic properties of bilayer FeBr2. It is found that the strength of interlayer magnetic coupling under different stacking configurations is predominantly governed by the spatial overlap of the pz orbitals of the nonmagnetic Br atoms. Among the considered stackings, the energetically most favorable AA configuration exhibits pronounced spin splitting when spin–orbit coupling is taken into account. Across the entire range of interlayer distances, AA-stacked FeBr2 preserves the interlayer antiferromagnetic coupling with an out-of-plane easy magnetization axis. As the interlayer distance decreases, the interlayer magnetic coupling is enhanced, while the magnetic anisotropy energy is reduced. In contrast, increasing the interlayer distance weakens the magnetic coupling but strengthens the magnetic anisotropy. This nonmonotonic behavior originates primarily from the competition between the electronic hopping-induced kinetic energy and the Pauli repulsion between adjacent layers. The present work provides an important route to manipulate the magnetic coupling and magnetic anisotropy in van der Waals magnets for spintronic applications.