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Electronic and magnetic properties of CoPc and FePc molecules on graphene: the substrate, defect, and hydrogen adsorption effects

Abstract

Transition metal phthalocyanines (TMPcs) are particularly appealing for spintronic processing and data storage devices as their structural simplicity and functional flexibility. To realize the effective control of the spins in TMPc-based systems, it is necessary to quantify how the structural and chemical environment of the molecule affects its spin center. Herein we perform a detailed investigation of electronic and spintronic properties of vertically stacked heterostructures formed by a CoPc or FePc adsorbed on a monolayer of graphene under the influences of the gold substrate, vacancies in graphene, and extra atomic hydrogen coordination on the TMPc. By using the density functional theory, we reveal that both the TMPc molecules prefer the carbon-top position on graphene, and the existence of the Au substrate enhances the stability of the adsorption, while this enhanced adsorption will not modify the molecular magnetism, maintaining it the same value as in the free standing case. Moreover, with the aid of a combination of DFT and ab initio wavefunction-based calculations, our results also indicate that the magnetic anisotropy of the FePc-graphene complex can be actively tuned by the Au substrate. Our calculations also show the defects in graphene including single and double vacancies can modify the magnetism of these heterostructures. In particular, the spin state of FePc can be tuned from S=1 to S= 2 with such defect engineering. A further spin state tunability can be achieved from a hydrogenation process, with the coordination of one extra hydrogen on Co-top site for CoPc and pyridinic N site for FePc, respectively, tuning the their spin states from S=1/2 to S=0 and from S=1 to S=2. These findings may prove to be instrumental for a rational design of future molecular spintronics devices integrated with two-dimensional materials.

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Supplementary files

Publication details

The article was received on 16 Nov 2018, accepted on 11 Feb 2019 and first published on 12 Feb 2019


Article type: Paper
DOI: 10.1039/C8CP07091A
Citation: Phys. Chem. Chem. Phys., 2019, Accepted Manuscript

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    Electronic and magnetic properties of CoPc and FePc molecules on graphene: the substrate, defect, and hydrogen adsorption effects

    Y. Wang, X. Li and J. Yang, Phys. Chem. Chem. Phys., 2019, Accepted Manuscript , DOI: 10.1039/C8CP07091A

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