Ferroelectric polarization tailored spin polarized electronic structure and magnetic anisotropy in two-dimensional ScSi₂N₄/CuInP₂S₆ multiferroic heterostructures

Abstract

Two-dimensional (2D) van der Waals (vdW) multiferroic heterostructures which consist of vdW intrinsic magnets and ferroelectrics plays an extremely important in novel 2D spintronic devices. In this paper, the electronic structure and magnetic anisotropy of 2D vdW ScSi2N4/CuInP2S6 heterostructure are systematically investigated using first-principles calculation. CuInP2S6 is a 2D ferroelectric material with out-of-plane polarization, and ScSi2N4 is a half-metal with ferromagnetic properties. After the ab initio molecular dynamics simulations, the structures of P↑ and P↓ states are stable. Both the P↑ and P↓ states of ScSi2N4/CuInP2S6 heterostructure are ferromagnetic half-metals. Biaxial strains modulate the electronic structure and magnetic properties of the ScSi2N4/CuInP2S6 heterostructure. With the application of compressive strains in P↓ state, the spin-up band crosses Fermi level and the P↓ state changes from half-metal to metal. The transition from half-metal to metal in P↑ state is realized at ε=-4% and ε=-6%. The magnetic anisotropy energy of the P↓ state can be enhanced by compressive strains of -2% and -4%. The P↓ state has the largest average planar of electrostatic potential is 0.819 eV at ε=-6%, which keeps the maximum electrostatic field between ScSi2N4 and CuInP2S6 monolayers. As the strain increases from -2% to -6%, the potential difference of P↑ state increases gradually. At +6% tensile strain, the band structure inversion occurred in both P↑ and P↓ states. These results demonstrate the potential of 2D vdW multiferroic heterostructures and can enrich the field of spintronic devices.