Binary transition metal nitride with a graphene-like structure and strong magnetic properties is rare. Based on the first-principles calculations, we design two kinds of MN4 (M =transition metal) monolayers, which are transition metal nitrides with a planar structure, made up of MN4 units aligned in the rhombic and square patterns. The two structural lattices have robust stability and good compatibility with different metal atoms, and the underlying mechanism is the combination of sp2 hybridization, coordinate bond, and π conjugation. With the metal atom changing from V, Cr, Mn, Fe to Co, the total charge of MN4 system increases by one electron in turn, which results in continuous adjustability of the electronic and magnetic properties. The planar ligand field is another feature of the two MN4 lattices, which brings about the special splitting of five suborbitals of 3d metal atom and gives rise to strong magnetism. Moreover, room-temperature ferromagnetism in square-CoN4 monolayer with the Curie temperatures of 321 K is determined by solving the Heisenberg model combined with Monte Carlo method.
@article{arxiv.2204.13551,
title = {Two-dimensional binary transition metal nitride $M$N$_4$ ($M$ = V, Cr, Mn, Fe, Co) with a graphene-like structure and strong magnetic properties},
author = {Shuo Zhang and Panjun Feng and Dapeng Liu and Hongfen Wu and Miao Gao and Tongshuai Xu and Xun-Wang Yan and Z. Y. Xie},
journal= {arXiv preprint arXiv:2204.13551},
year = {2024}
}