Prediction of intrinsic room-temperature ferromagnetism in two-dimensional CrInX2 (X = S, Se, Te) monolayers

Abstract

Herein, using density functional theory, novel two-dimensional (2D) CrInX₂ (X = S, Se, Te) structures are predicted to be practical ferromagnetic (FM) semiconductors. Phonon vibrations and molecular dynamics simulations verified their structural and thermodynamic stability. Sizable fully spin-polarized band gaps of 1.03 and 0.69 eV are found for CrInS₂ and CrInSe₂, while CrInTe₂ exhibits half-metallic band nature (at 0 K with a perfect lattice). The high magnetic anisotropy energies are responsible for their long-range spin polarization. The Curie temperatures (T_c) are estimated to be 347, 397 and 447 K for CrInS₂, CrInSe₂ and CrInTe₂, respectively, all well above the room-temperature. The high T_c originates from unusual FM direct exchange, the efficient super-exchange coupling between neighboring Cr e_g-orbitals with zero virtual exchange gaps and the presence of dual Cr–X–Cr super-exchange channels. Our systematic study of the CrInX₂ monolayer suggests that it could be a promising material for spintronics applications.