Pairing of π electronic state structures with functional or metallic atoms makes them possible to engineer physical and chemical properties. Herein, we predict the reorientation of magnetization of Co on hexagonal BN (h-BN) and graphene multilayers. The driving mechanism is the formation of the tetrahedral bonding between sp 3 and d orbitals at the interface. More specifically, the intrinsic π-bonding of h-BN and graphene is transformed to sp 3 as a result of strong hybridization with metallic d z 2 orbital. The different features of these two tetrahedral bondings, sp 2 and sp 3 , are well manifested in charge density and density of states in the vicinity of the interface, along with associated band structure near theK valley. Our findings provide a novel approach to tailoring magnetism by means of degree of the interlayer hybrid bonds in 2D layered materials.

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Employing first-principles electronic structure calculations, we have studied the electric field controls of magnetism and magnetic anisotropy energy (MAE) of the Fe adatoms on ferroelectric BaTiO3 and PbTiO3 surfaces. Remarkably, those effects exhibit dependence of the level of coverage as well as adsorption site of Fe atoms. While the magnitude of MAE is shown tunable by ferroelectric polarization in the full coverage of Fe monolayer, the direction of magnetization undergoes a transition from perpendicular to in-plane for the half or lower coverages. This magnetization reorientation is mainly ascribed to the site-dependent Fe d–O p hybridization, as a consequence of the formation of FeTiO2 layer at the surface.

Magnetism of tavorite and triplite LixFeSO4F (x = 0, 1/2, and 1) has been studied using the first-principles density-functional theory. It was found that an antiferromagnetic ordering is more stable compared to a ferromagnetic state and the energy difference between two magnetic states is reduced when the lithium is intercalated, being consistent with a recent experimental observation of lowering Neel temperature from 100 K of FeSO4F to 25 K of LiFeSO4F. Furthermore, the magnetic moment of 3.8 μB/Fe for FeSO4F was found to be oriented along the [010], whereas that (4.3 μB/Fe) of LiFeSO4F along the [001]. And the magnetic moment and magneto-crystalline anisotropy were found to be insensitive upon different atomic structures, which imply that the lithium intercalation affects the spin orientation of Fe rather than the interplay between lattice and magnetism suggested by an experiment.

Two-dimensional (2D) structures that exhibit intriguing magnetic phenomena such as perpendicular magnetic anisotropy and its switchable feature are of great interests in spintronics research. Herein, the density functional theory studies reveal the critical impacts of strain and external gating on vacancy-induced magnetism and its spin direction in a graphene-like single layer of zinc oxide (ZnO). In contrast to the pristine and defective ZnO with an O-vacancy, the presence of a Zn-vacancy induces significant magnetic moments to its first neighboring O and Zn atoms due to the charge deficit. We further predict that the direction of magnetization easy axis reverses from an in-plane to perpendicular orientation under a practically achievable biaxial compressive strain of only ~1-2% or applying an electric field by means of the charge density modulation. This magnetization reversal is mainly driven by the strain- and electric-field-induced changes in the spin-orbit coupled d states of the first-neighbor Zn atom to a Zn-vacancy. These findings open interesting prospects for exploiting strain and electric field engineering to manipulate magnetism and magnetization orientation of 2D materials.