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ZnO hexagonal bipods have been synthesized by a hydrothermal method using NaAOT as template. Co-doped ZnO bipods show obvious room temperature ferromagnetic behaviours. Phase composition, microstructure, and x-ray photoemission spectra analysis indicate that there is no Co cluster exsisting in the samples, and the ferromagnetism observed in Co-doped ZnO bipods should be intrinsic. Photoluminescence spectra indicate there exist a large amount of oxygen vacancies in the ZnO bipods. The ferromagnetism can be tuned by the content of Co ions, which should be closely realted to the magnetic coupling interaction between the Co2+ 3d spins and the electrons trapped at oxygen vacancies. [ABSTRACT FROM AUTHOR]

Polycrystalline NiO-based thin films with Li or/and transition metal ions (V, Cr, Mn, Fe, Co, Cu, Zn) doping have been prepared by a sol-gel spin-coating method. Magnetization measurements reveal that V-, Fe-, and Mn-doped NiO thin films show obvious room-temperature ferromagnetic behaviors and ferromagnetic properties can be enhanced by the Li co-doping. Microstructure and X-ray core-level photoemission spectra analysis indicate that the ferromagnetism was not from the impurity TM metal cluster and may be ascribed to double exchange coupling effects via Li-induced holes. [ABSTRACT FROM AUTHOR]

Nanostructured BiFeO3 particles have been synthesized by a hydrothermal method, and the effects of particle size on photocatalytic activity and magnetic property of BiFeO3 were investigated. The optical absorption spectra indicate that the band-gap energy increases with decreasing crystalline size due to the quantum-size effect. The enhancement of room-temperature weak ferromagnetism can be observed in nanoscale BiFeO3 particles, which should be attributed to the size-confinement effect on the magnetic ordering. In addition, BiFeO3 nanoparticles with diameter about 5 nm show good photocatalytic performance by photodegradation of Congo red under visible-light (λ>400 nm) irradiation. [ABSTRACT FROM AUTHOR]

Highly orientated Co-doped Zn( Mg, Cd) O thin films have been prepared on Si (001) substrate using pulsed laser deposition (PLD). Our results indicate that Mg and Cd-doping can tune the bandgap of ZnO thin film. Apparent room-temperature ferromagnetism is observed in these films, which can be modified by the bandgap of ZnO. A narrow bandgap enhances the ferromagnetism of the films through the Cd-doping, and wide bandgap does the opposite through the Mg-doping, which may be ascribed to the ferromagnetic ( FM) exchange interaction between the 3 d states of magnetic Co ions and the impurity band. These experimental results provide some new evidence that the ferromagnetism in Co: ZnO is closely related to crystal defects and improve our knowledge about ferromagnetism in dilute magnetic oxides. [ABSTRACT FROM AUTHOR]

LixNi0.97-xFe0.03 nanofibers with different Li doping concentration have been synthesized by electrospinning method. The phase composition and microstructure analysis show that Fe and Li doping has no influence on the phase structure and morphology of NiO nanofibers, which reveal that the doped Fe and Li have been incorporated into the NiO host lattice. All the Li and Fe co-doped NiO nanofiber samples show obvious room-temperature ferromagnetic properties. The saturation magnetization can be enhanced with increase of the Li doping concentration. This phenomenon can be ascribed to the fact that the hole doping makes ferromagnetic coupling interactions between the holes and localized Fe 3d states more efficient. [ABSTRACT FROM AUTHOR]

Polycrystalline ZnO-based thin films with Li and/or Co doping have been prepared by a sol-gel spin-coating method on silicon substrates. Magnetization measurements reveal that Li-doped ZnO film shows paramagnetic behavior. However, the Co-doped ZnO thin films show obvious room-temperature ferromagnetic properties, and ferromagnetic properties can be enhanced by the Li codoping, which may be ascribed to indirect exchange via Li-related defects. All ZnO-based films exhibit ferroelectric behavior, and ferroelectric properties can be tuned by the dopants. [ABSTRACT FROM AUTHOR]

The authors present the structure transformation and magnetic properties of Bi1-xLaxFeO3 (x=0.0–0.15) ceramics prepared by a conventional solid-state reaction processing. Magnetic measurements reveal that remnant magnetization of 15% La-doped BiFeO3 has enhanced about 20 times as compared to pure BiFeO3. It is the structural phase transition (R3c–C222) near x=0.15 that destructs the spin cycloid, and thus enhances the ferromagnetic properties significantly. In these Bi1-xLaxFeO3 ceramic samples, besides the known antiferromagnetic Néel temperature TN1∼615 K, another Néel temperature TN2∼260 K can be observed due to the trace impurity phase of Bi2Fe4O9 in these ceramic samples. [ABSTRACT FROM AUTHOR]

Li and Fe codoped NiO thin films (LixNi0.98-xFe0.02O, x=0–0.05) were obtained by a sol-gel spin-coating method on silicon substrates. Phase composition and microstructure analysis indicated that the film samples contained 20–30 nm sized NiO particles. With increasing Li-doping concentration, the current density of the films increased due to the increase of hole carriers. Magnetization measurements revealed that all the thin films showed room-temperature ferromagnetic properties and could be enhanced by Li doping, which should be due to the fact that hole doping makes ferromagnetic coupling interactions between the hole carriers and localized Fe 3d spins more efficient. [ABSTRACT FROM AUTHOR]

Corrections to the article "Ferromagnetism in antiferromagnetic NiO-based thin films" that was published in the 2011 issue are presented.

Abstract: Mg/Cd doped Mn:ZnO thin films have been prepared by a sol-gel method. Our results indicate that Mg and Cd-doping can tune the bandgap of ZnO film (3.17-3.30eV), and all of these thin films show room temperature ferromagnetic behaviors. As the bandgap of ZnO-based thin films changes, it effects the strength of the magnetic exchange interaction in the transition metal doped ZnO films, which results in the tunable ferromagnetism. This may be a practical way to achieve appropriate dilute magnetic semiconductor materials for future spintronic devices. [Copyright &y& Elsevier]

Abstract: Nanostructured ZnO powders with various morphologies have been prepared by the hydrothermal and chemical precipitation methods. Our results reveal that these nanostructured ZnO particles exhibit obvious room-temperature ferromagnetism, while microbipods show paramagnetic behavior. Photoluminescence spectra indicate that oxygen vacancies (Vo) exsit in these nanostructured ZnO particles. The polarized impurity band associated with Vo defects provides the necessary ferromagnetic coupling, and the variable concentrations of Vo result in the tunable magnetic behaviors in these nanostructured ZnO particles. [Copyright &y& Elsevier]