Comparative study of electronic and magnetic properties of MPc (M = Fe, Co) molecules physisorbed on 2D MoS2 and graphene
Abstract
In this paper, we have done a comparative study of electronic and magnetic properties of iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc) molecules physisorbed on monolayer of MoS2 and graphene by using density functional theory. Various different types of physisorption sites have been considered for both surfaces. Our calculations reveal that the MPc molecules prefer the S-top position on MoS2. However, on graphene, FePc molecule prefers the bridge position while CoPc molecule prefers the top position. The MPc molecules are physisorbed strongly on the MoS2 surface than the graphene ( 2.5 eV higher physisorption energy). Analysis of magnetic properties indicates the presence of strong spin dipole moment opposite to the spin moment and hence a huge reduction of effective spin moment can be observed. Our calculations of magnetic anisotropy energies using both variational approach and 2nd order perturbation approach indicate no significant changes after physisorption. In case of FePc, an out-of-plane easy axis and in case of CoPc, an in-plane easy axis can be seen. Calculations of work function indicate a reduction of MoS2 work function 1 eV due to physisorption of MPc molecules while it does not change significantly in case of graphene.