Ferromagnetic semiconductor nanotubes with room Curie temperatures

Realizing ferromagnetic semiconductors with high Curie temperature TC remains a challenge in spintronics. Recent experiments have obtained some two-dimensional (2D) room temperature ferromagnetic metals, such as monolayers CrS2 and VSe2. Inspired by the recent experimental progress on the nanotubes based on 2D van der Waals non-magnetic transition-metal dichalcogenides, magnetic nanotubes based on monolayer ferromagnetic materials are highly possible. Here, by the density functional theory calculations, we proposed a way to obtain a high TC ferromagnetic semiconductor in magnetic nanotubes. Some high TC ferromagnetic semiconductors are predicted in the MX2 nanotubes (M = V, Cr, Mn, Fe, Co, Ni; X = S, Se, Te), including CrS2 and CrTe2 zigzag nanotubes with a diameter of 18 unit cells, showing TC above 300 K. In addition, due to the strain gradient in the walls of nanotubes, an electrical polarization at the level of 0.1 eV/Å inward of the radial direction is obtained. Our results propose a way to obtain high-temperature ferromagnetic semiconducting nanotubes based on experimentally obtained 2D high TC ferromagnetic metals.