Electronic structure and magnetism of monolayer Janus transition metal dihalides

Based on first-principles calculations, the evolution of the electronic and magnetic properties of transition metal Janus dihalides MXY (M= V, Mn, Fe, Co, Ni; X, Y = Cl, Br, I) is analyzed at the monolayer limit. A variety of magnetic ground states is obtained as a result of the competition between direct exchange and superexchange. We show how structural symmetry-breaking plays a crucial role in the magnetic and electronic properties of 2D magnetic materials.