  In this work, we theoretically report a new large family of two-dimensional
(2D) transition metal sulfides $M$$_{2}$S with MXene structure in 2H and 1T
phases, which we name as MSene. Twenty-four out of fifty-eight MSenes are
proved to be stable. Notably, this family includes twelve superconducting (SC)
materials, seven SC topological metals (SCTMs), four charge density wave (CDW)
materials, and five magnetic materials including one ferromagnetic (FM) and
four antiferromagnetic (AFM) materials. For example, 2H-Mo$_{2}$S is a SCTM
which exhibits SC critical temperature ($T_{c}$) of 10.2 K and nontrivial
topological properties; 1T-Hf$_{2}$S is a CDW material with the CDW originating
from electron-phonon coupling. The CDW can be suppressed by compressive strain,
leading to the emergence of superconductivity; 2H-Cr$_{2}$S and 1T-Mn$_{2}$S
show FM and AFM properties, respectively. Thus, the new large family we
predicted shows rich physical properties and significantly expands the
repertoire of 2D materials. It serves as a novel platform for investigating the
competition or coexistence of multiple orders such as SC, CDW, FM, AFM and
topological orders in 2D materials.
