Giant magnetism in punched zigzag-edged triangular-shaped graphene nanodisks

We observe, for the first time, a very large magnetism in the nano-sized (7–27 Å) punched graphene nanodisks (PGNDs) i.e., zigzag-edged triangular PGNDs (ZET-PGNDs). A first-principles method has been employed to investigate their electronic and magnetic properties. Similar to a regular or unpunched ZET-GND where the spin value scales with the linear dimension of the ZET-GND arising from the topological frustration of the π bonds and the induced spin distributions in graphene structures, the magnetic moment in a PGND increases with its size very rapidly depending on the type of punching. Two types of the punched nanodisks have been discussed. In one type of PGND, the magnetic moment of the punched out smaller GND is added to the magnetic moment of the host GND and the resultant net magnetism is, thus, equal to the sum of the magnetic moments of the host GND and that of the punched out smaller GND. In the other type of the PGND, the magnetic moment of the punched out smaller GND is subtracted from the magnetic moment of the host GND and the net value of the magnetic moment is the difference of the magnetic moments of the host GND and that of the punched out smaller GND. One may, thus, enhance the magnetism of a GND by making an appropriate choice of the punching. It may have large magnetic moments in the passivated ZET-PGNDs beyond the nanoscale at room temperature. These punched graphene fragments may be employed for the preparation of several kinds of the electronic and spintronic devices possessing exotic features.