Jahn-Teller Effects and Spintronic Behaviors in a Ti-Doped ScSI Monolayer

The geometric and electronic properties of the recently emerged two-dimensional material ScSI substitutionally doped by Ti atoms in one atomic layer are studied employing density functional theory. The Jahn-Teller effect is greatly enhanced around a Ti dopant due to the distorted octahedral geometry of its coordinate atoms. Besides the much enlarged energetic separation between e(g) and t(2g) orbital groups, the d(yz) orbital separates from the d(xz) and d(x)(y )orbitals in the t(2g) orbital group. The material becomes a half-semiconductor when one Sc atom is replaced by a Ti atom in each 2 x 2 supercell, and only the spin-up d(yz) orbital is occupied. The material remains a half-semiconductor if the Ti dopants align in a specific direction at higher doping concentrations and may convert into a half-metal otherwise. It becomes a strongly magnetized metal when the Sc atoms in a whole atomic layer are replaced by Ti atoms. Ti-doped ScSI is expected to be promising in the application of spintronics.