Effects of charge ordering in the octahedral sites of Fe3O4 and CoFe2O4 on their magnetostrictions are investigated using the density functional theory plus U approach. Precise description of charge ordering was found to be crucial in determining only band-gaps of Fe3O4 and CoFe2O4, but not other physical properties such as lattice constant, magnetic moment, and magnetostriction. And Co configuration in CoFe2O4 is important in determining its magnetostriction; the most stable configuration results in substantially enhanced magnetostriction (−245 ppm), compared to that (−25 ppm) of Fe3O4, in consistent with experiments.

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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Herein, using first-principles calculations, we predict spin reorientation from in-plane to out-of-plane magnetization of an individual Fe magnet at the monophosphor vacancy in two-dimensional blue phosphorous (2D blue-P) by a few percent of tensile strain. We further reveal that this magnetization reversal is associated with the spin-state transition of Fe 3d5 state from low-spin (1 ) to high-spin state (5 ), which occurs at the same tensile strain imposed into 2D blue-P, from the Ligand field theory analyses in the unpaired electron counts. The underlying mechanism for both the spin-state transition and spin-reorientation phenomena is the strain induced changes in the spin–orbit coupled adatomic and states through the strong hybridization with the P-3p  orbitals. These findings open interesting prospects for exploiting stain engineering of 2D materials to manipulate magnetism and magnetization orientation of single-molecule magnets adsorbed on it.

Magnetic anisotropy in the boron nitride monolayer doped by 3d transitional metal substitutes at boron-site J. Appl. Phys. 113, 17C304 (2013); 10.1063/1.4798478 Electronic structures of an epitaxial graphene monolayer on SiC(0001) after metal intercalation (metal = Al, Ag, Au, Pt, and Pd): A first-principles study Appl. Phys. Lett. 100, 063115 (2012); 10.1063/1.3682303 Noncollinear magnetism, magnetocrystalline anisotropy, and spin-spiral structures in Fe ∕ W ( 110 )Magnetism and magnetocrystalline anisotropy (MCA) of 4d and 5d transition metal monolayers have been investigated in the presence of a Co(0001) substrate using first-principles electronic structure calculations. Magnetization of Co-group elements undergoes a transition from an in-plane to perpendicular MCA on Co(0001), whose energies (E MCA ) are þ0.75 meV/cell and þ3.67 meV/ cell for Rh/Co(0001) and Ir/Co(0001), respectively. On the other hand, the Fe-group Ru/Co(0001) and Os/Co(0001) exhibit the in-plane MCA with antiparallel spin moments to that of the Co substrate. From band analysis, enhancement of MCA in the Ir/Co(0001) is mainly due to the Ir atom by hm ¼ 0jl x jm ¼ 61i matrix in the "#-channel, where negative MCA found in Os/Co(0001) is due to Co with dominant contribution from hm ¼ 0jl x jm ¼ 61i and hm ¼ 62jl x jm ¼ 61i matrices in the ##and "#-channel, respectively. The significant enhancement of E MCA in Rh/ and Ir/ Co(0001) is ascribed to larger spin-orbit coupling of 4d and 5d orbitals, mainly by coupling between m ¼ 0 and m ¼ 61 states. V C 2015 AIP Publishing LLC. [http://dx.