  MnSn monolayer synthesized recently is a novel two-dimensional ferromagnetic
material with a hexagonal lattice, in which three Mn atom come together to form
a trimer, making it remarkably different from other magnetic two-dimensional
materials. Most impressively, there happens a sharp increase of Curie
temperature from 54 K to 225 K when the number of layers increase from 1 to 3.
However, no quantitative explanation is reported in previous studies. Herein,
by means of first-principle calculations method and Monte carlo method, we
demonstrate that strong interlayer ferromagnetic coupling is the essential role
in enhancing its critical temperature, which act as a magnetic field to
stabilize the ferromagnetism in the MnSn multilayers.
