Rock-salt structured single-phase Ni0.98Fe0.02O and Ni0.93Fe0.02Li0.05O thin films with room temperature ferromagnetism were grown by pulsed laser deposition. It is found that the Li codoping into Ni0.98Fe0.02O significantly increases the saturation magnetic moment by a factor of 2, i.e., from 0.32μB∕Fe rising to 0.67μB∕Fe. The x-ray absorption fine structure spectral analyses at Fe and O K edge reveal that in both samples, the impurities are substitutionally incorporated into the NiO host. The first-principles calculations show that substitutionally doping Li ions into NiO leads to a strong hybridization between the Fe 3d states and the spin-split acceptor band at the Fermi level. As a result, the Fe 3d electron configuration is altered and the effective magnetic moment per Fe ion is enhanced.

Single-atom catalysts (SACs) and single-cluster catalysts (SCCs) have aroused significant interest in heterogeneous catalysis. Transition metal (TM) atoms doped on metal-oxide surfaces provide an opportunity for tuning their electronic, magnetic, and catalytic properties. Herein, the structural, energetic, electrochemical, electronic, and magnetic properties of TMs doped at copper and oxygen vacancies on Cu 2 O surfaces are systemically studied using density functional theory calculation with dispersion correction. Among the 174 systems studied, we found 60 new stable potential SACs and SCCs. It is found that SACs prefer to form on the Cu 2 O(111) surface by replacing the second-layer coordination-saturated copper atom, while SCCs prefer to form on the Cu 2 O(110) surface by replacing the second-layer oxygen atom. Binding and formation energies of SACs and SCCs along d-series TMs show a shape of two peaks, which is caused by respective majority-and minority-spin electron occupancy of d orbitals, and formation of SACs is much more favorable than formation of SCCs on three low-index Cu 2 O surfaces. The charge transfer decreases along the d-series from left to right across the periodic table due to the orbital energy decrease, while the spin states of TMs for SACs and SCCs on Cu 2 O surfaces show periodic variation trends along d-series. Our results provide fundamental knowledge of TMs doped on Cu 2 O surfaces, which helps design new atomically precise heterogeneous catalysts via SACs and SCCs.

Orbital and spin moments of Co atoms in films of different thickness deposited by magnetron-sputtering on silicon wafers have been investigated by use of soft x -ray magnetic circular dichroism in absorption. Layers with thickness 2nm, 10nm and 30nm are covered by 0.8—1nm of protection overlayer. Orbital and spin momen ts of 0.249—0.195μB and 1.230—1.734μB are found from X MCD sum rules. Increase in orbital moments and decrease in spin moments are obse rved with reducing cobalt film thickness. There is a ratio variation from 0.101 to 0.168 of orbital moment to total moment, that is, contribution of orbital mom ent of cobalt atoms to total moment in 2nm film is 83% greater than that in the 30nm film.

X-ray magnetic circular dichroism (XMCD) in the absorption of the single-crystal iron thin film deposited epitaxially on MgO substrate is studied to get the spin and orbital moment. The experiments show that along with different crystal axes, the change of orbital moment of Fe atoms is about 600%, the change of the spin moment is only about 50%, but the change of total moment is not so large. Researching the anisotropy by means of routine methods, the relation between the magnetic moment and the anisotropy of the thin film is studied.

Pulsed laser deposition (PLD) method was used to fabricate Ni1-xFexO (x=0.02，0.05) dilute magnetic semiconductor thin films with room temperature ferromagnetism. For the Ni0.98Fe0.03O sample with a lower Fe content，the crystalline structures of the Ni1-xFexO films are of the NaCl type as determined by X-ray diffraction. For the Ni0.95Fe0.05O sample with a higher Fe content，some additional weak diffraction peaks corresponding to α-Fe2O3 phase can be observed. From the X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS)， it is shown that the doped Fe impurities in Ni0.98Fe0.02O are substitutionally incorporated into the NiO host and no secondary phases with room temperature ferromagnetism are found. These results show the intrinsic ferromagnetism of the Ni1-xFexO samples.