Magnetic properties in atomic Co manipulated graphitic carbon nitride

Since discovery of graphene which has unique electronic properties, much effort has been paid to invoke other properties like optical and magnetic for different applications. Considering spintronics applications, it is wise to develop magnetic properties in 2D materials as most of them are diamagnetic and have superior electronic properties. Previously, we have manipulated transition metal atoms (TM) on graphene surface and observed very interesting magnetic properties. But the limitation of graphene is to manipulate single TM atom on the hole position in carbon honeycomb structure. Therefore, to manipulate multi atoms on the hole position for investigating the effect of interaction between the TM atoms as well as with the carbon network structure, in the present work, we have manipulated single to multi atoms (Cobalt atoms) in the large cavity of graphitic carbon nitride (g-C3N4). We have controlled the number of atoms in the cavity by varying the concentration of ‘Co’ atoms. We have synthesized three samples S1, S2 and S3 with lower, medium and highest concentrations of ‘Co’ atoms, respectively. For lower concentration one atom/cavity is more probable. In case of medium concentration most of the cavities are filled by single atom while few cavities are filled by multi atoms and for the highest concentration most of the cavities are filled by multi atoms. It is seen that all the samples show ferromagnetism at low temperature region but at higher temperature region either paramagnetic or antiferromagtic behaviour is obtained depending upon the concentration of ‘Co’ atoms. The long range ordering is explained on the basis of the interaction between the magnetic moments generated in g-C3N4 lattice due to charge transfer from ‘Co’ atom to g-C3N4 lattice via π-electrons. We believe that TM atom embedded g-C3N4 having controlled magnetic properties could be a promising material for spintronics applications.