  Here, we study the magnetism of the distorted 1T-TcX2 (X=S,Se) based on
first-principles calculation. The magnetism originates from the hole doping due
to the density of states near the valence band edge having van Hove singularity
feature. The calculated results show that the TcS2 monolayer can develop an
interesting ferromagnetic (FM) half-metallic phase with tunable
spin-polarization orientation. The FM half-metallicity and magnetic moments of
the hole-doped TcS2 monolayer are primarily derived from the p orbital of S
atoms, then, a FM ground phase with a high Curie temperature (Tc) (larger than
800 K) is obtained due to the strong Sp-Sp direct exchange interaction. The
magnetic order is robust against thermal excitations at finite temperatures
because of magnetic anisotropic energy. In the TcS2 bilayer, the electrons near
Fermi level are redistributed when introducing the interlayer interaction,
which suppresses the ferromagnetism induced by hole doping. The ferromagnetism
can be recovered when the interlayer interaction is weakened.
