Two-dimensional osmium tetrafluoride with non-collinear ferromagnetism

Two-dimensional (2D) transition metal tetrafluoride materials usually demonstrate antiferromagnetic or altermagnetic ordering, exhibiting potential in spintronics applications. In this work, we systematically investigate the structural, electronic, and magnetic properties of osmium tetrafluoride (OsF4), a member of 2D transition metal tetrafluoride material family, through comprehensive hybrid functional theory calculations. Our data indicate the mechanical, dynamical, and thermodynamical stability of the 2D OsF4. Band structure calculations incorporating spin–orbit coupling reveal that 2D OsF4 behaves as an indirect bandgap semiconductor with a forbidden gap of 2.75 eV. Through detailed analysis of the non-collinear ferromagnetic ground state, we quantitatively determine the dominant magnetic interactions, including exchange coupling, Dzyaloshinskii–Moriya interaction, and magnetic anisotropy energy, demonstrating the prevalence of nearest-neighbor magnetic coupling. Monte Carlo simulations based on the derived Heisenberg model parameters predict a relatively low Curie temperature of 18 K in 2D OsF4. Furthermore, the emergence of a nonzero magnon gap at the Γ point in the calculated magnon spectrum provides direct evidence of significant magnetic anisotropy effects in this system.