Novel mechanism for weak magnetization with high Curie temperature observed in H-adsorption on graphene

To elucidate the physics associated with the magnetism observed in nominally nonmagnetic materials containing only sp-electrons, we have developed an extreme model to simulate the adsorption of H (in a straight-line form) on graphene. Our first principles calculations for the model result in a ferromagnetic ground state at a high temperature with a magnetic moment of one Bohr magneton per H atom. The removal of p  _z -orbitals from sublattice B of graphene introduces p  _z -vacancies. The p  _z -vacancy-induced states are created not because of the variations in interatomic interactions but because of the p  _z -orbital imbalance between two sublattices (A and B) of the conjugated p  _z -orbital network. Therefore, some critical requirements should be satisfied to create these states (denoted as [Formula: see text]) to avoid further imbalances and to minimally affect the conjugated p  _z -orbital network. The requirements for the creation of [Formula: see text] can be given as follows: (1) [Formula: see text] consists of p  _z -orbitals of only the atoms in sublattice A, (2) the spatial wavefunction of [Formula: see text] is antisymmetric, and (3) in principle, [Formula: see text] extends over the entire crystal without decaying, unless other p  _z -vacancies are encountered. Both the origin of spin polarization and the magnetic ordering of the model can be attributed to the aforementioned requirements.