Exploring magnetoelectric effects in 1 T − FeCl 2 / bilayer − GaSe multiferroic heterostructures

We report investigations into a new kind of multiferroic heterostructure consisting of a two-dimensional ferromagnetic 1T-phase FeCl₂ monolayer and a sliding-ferroelectric bilayer-GaSe using first principles calculations. In this study, we determine the structural and electronic properties, energy band alignments, magnetic anisotropy, binding energies, interfacial charge transfer, and electric dipole moments of different stackings of 1T-FeCl₂/bilayer-GaSe. The generalized gradient approximation of the Perdew--Burke--Ernzerhof (GGA-PBE) and Heyd-Scuseria-Ernzerhof (HSE) functionals predict half-metallicity, while the regularized-restored strongly constrained and appropriately normed (r²SCAN) functional opens a band gap in the spin-down Fe $3d$ states upon releasing symmetry constraints. The total magnetic moment of the Fe²⁺ ion (4.00 B) remains unchanged in the heterostructures for both polarization directions. The magnetic anisotropy energy of all stacking configurations considered indicates an in-plane easy magnetization axis, arising from the Fe-dxz orbitals under both polarization directions. All stackings exhibit Ohmic-type electrical conductivity, indicating charge transfer across the interfaces. Hence, this study presents a theoretical framework for designing artificial multiferroics that simultaneously maintain both ferromagnetic and ferroelectric properties, enabling future technological developments.