Two-Dimensional Co(2)S(2) monolayer with robust ferromagnetism

Design and synthesis of two-dimensional (2D) materials with robust intrinsic ferromagnetism is highly desirable due to their potential applications in spintronics devices. In this work, we identify a new 2D cobalt sulfide (Co(2)S(2)) material by using first-principles calculations and particle swarm optimization (PSO) global structure search. We show that the 2D Co(2)S(2) is most stable in the litharge type tetragonal structure with space group of P4/nmm. The elastic constants, phonon spectrum, and molecular dynamics simulation confirm its mechanical, dynamical and thermal stability, respectively. It is also found that Co(2)S(2) monolayer is a ferromagnetic metal with a Curie temperature up to 404 K. In addition, we propose a feasible procedure to synthesize the Co(2)S(2) monolayer by chemically exfoliating from bulk TlCo(2)S(2) phase.