Theoretical insights into magnetization in graphene containing single and interacting nanoporous defects

• Published in: Physica. E, Low-dimensional systems & nanostructures Vol. 128; p. 114564
• Main Authors: Nkou, F.B.S., Douma, D.H., Malonda Boungou, B.R., Raji, A.T., Kenmoe, S., M'Passi Mabiala, B.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2021
• Subjects: Dangling bonds; Induced magnetism; Nanoporous graphene; Spintronics; Two-dimensional materials; Two-dimensional materials; Dangling bonds; Induced magnetism; Nanoporous graphene; Spintronics
• DOI: 10.1016/j.physe.2020.114564
• ISSN: 1386-9477

Defect-induced magnetism in two-dimensional materials continues to attract attention due to potential applications in spintronics. Using density-functional theory (DFT) approach, we report on the magnetization in graphene containing carbon vacancy defects, i.e., nanoporous graphene. We consider single nanopores consisting of up to ten vacancies and interacting nanopores consisting in vacancy pairs, divacancy pairs and vacancy-divacancy pairs, separated at varying distances. We found that the interactions between the nanopores weaken as their separation increases such that the formation energy tends to the value for the single nanopore while the magnetic moment tends to the sum of individual magnetic moments. Introducing additional nanopore to a pre-existing nanopore may enhance graphene's magnetic moment, however, the nanopores may also interact to induce zero magnetization. The enhancement, reduction or total annihilation of the magnetic moments may be adduced to interactions between the individual nanopores resulting in the saturation of the dangling bonds and/or the realignment of the electrons responsible for the magnetization. Also, our calculated values of induced magnetic moment of different single nanopores enable us to determine an empirical model for predicting the total magnetic moment as a function of nanopore size. The model is able to produce the magnetic moment of small and large nanopore sizes which are in excellent agreement with the DFT calculated values. Finally, we found our results to be consistent with recent experimental studies on magnetic response of graphene containing vacancies introduced via a synthesis process or ion irradiation, respectively. •An empirical model which captures the variation of magnetic moment with the number of vacancies in graphene is proposed.•Interactions between nanopores weaken as their separation increases.•Introducing additional nanopores to a pre-existing one in graphene may enhance, reduce or annihilate its magnetic moment.•Zero magnetization in porous graphene may be due to strong inter-pore interactions and the saturation of dangling bonds.•Our theoretical results support recent magnetic measurements in synthesized graphene containing vacancies.