First-Principles Study of Magnetism in Bilayer Manganese Phthalocyanine*

Magnetism in two dimensional materials has recently become a hot research topic due to its potential applications in spintronics and physical properties that arise from low dimensionality. Previously, monolayer manganese phthalocyanine (MnPc) has been synthesized experimentally, and theoretical studies have revealed that its magnetic properties can be tuned by substituting cations, applying biaxial strain, and imposing a gate voltage. In this first-principles study we examine the properties of bilayer MnPc using density functional theory (DFT). According to our simulations, Mn-to-Mn on-top stacking is found to be energetically less favorable, and we determine the stable position of the top layer relative to the bottom layer. When bilayer MnPc is in its ground state, both MnPc layers are in the Neel anti-ferromagnetic (NAF) state, although the ground state of monolayer MnPc is Collinear Antiferromagnetic (CAF), indicating that the interlayer magnetic coupling is very important. We will discuss further the nature of intra- and inter-layer magnetic couplings.