Comparative study of electronic and magnetic properties of iron and cobalt phthalocyanine molecules physisorbed on two-dimensional 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 M Pc 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 M Pc 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 2 nd 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 M Pc molecules while it does not change significantly in case of graphene.

Graphene–Iron(II) Phthalocyanine Hybrid Systems for Scalable Molecular Spintronics

“…The adsorption of activated FePc (E ad (2) ) is presented (see eq 5) in the main text. Our findings concerning the role of vdW interactions agree to large extent with the recent studies of other authors 42,56,68 dealing with the MPcs on 2D substrates. For example, PBE+U +TS calculations by Haldar et al 56 for flat adsorption of the FePc in three different positions above the graphene plane − Top, Bridge, and Hex − give the absorption energies of −3.38, −3.40, and −3.36 eV, respectively.…”

“…Having in mind the results of our recent studies 67 and also recent papers on similar hybrid structures involving TMPc and graphene, 42,56,68 we have performed some calculations, for the systems studied in the present work, employing vdW corrections within the Grimme and Tkatchenko−Scheffler schemes to the standard PBE. We indicate these approaches as PBE, PBE+D2, and PBE+T-S, and they seem to be commonly used in the studies of the dispersive force effects.…”

Ab initio theory of graphene-iron(II) phthalocyanine hybrid systems as scalable molecular spintronics

“…The Hamiltonian written above describes the relation between magnetic energy and the orientation of individual spins with respect to their environment, or in the other words, the MAE of the system. In the case of organometallic structures the performance of conventional DFT methods in accurate prediction of the MAE is rather poor [52][53][54] mainly due to the static correlation error 55 . The discrepancy between DFT prediction and the experiment for G-FePc composites can even reach one order of magnitude 42 .…”

Quasiparticle electronic structure of phthalocyanine:TMD interfaces from first-principles $GW$

“…Although many-body perturbation theory (MBPT), such as the GW formalism [21][22][23] , has been very successful [24][25][26] in resolving the gap problem of DFT 27,28 , its relatively high computational cost hinders its routine applications in large systems such as the interfaces formed between (metallo)phthalocyanines and monolayer TMDs. As a result, most prior computational studies of the phthalocyanine:TMD interfaces still employ DFT, with different complexities such as semi-local functionals 17,29 , hybrid functionals 3,30 or the DFT+U approach 31 .…”