Patterning graphitic C-N sheets into a kagome lattice for magnetic materials

We propose porous C-N-based structures for biocompatible magnetic materials that do not contain even a single metal ion. Using first-principles calculations based on density functional theory, we show that when patterned in the form of a kagome lattice, nonmagnetic g-C₃N₄ not only becomes ferromagnetic but also its magnetic properties can be further enhanced by applying external strain. Similarly, the magnetic moment per atom in ferromagnetic g-C₄N₃ is increased three fold when patterned into a kagome lattice. The Curie temperature of g-C₃N ₄ kagome lattice is 100 K, while that of g-C₄N₃ kagome lattice is much higher, namely, 520 K. To date, all of the synthesized two- and three-dimensional magnetic kagome structures contain metal ions and are toxic. The objective of our work is to stimulate an experimental effort to develop nanopatterning techniques for the synthesis of g-C₃N ₄- and g-C₄N₃-based kagome lattices.