Influence of structure characteristics on room temperature ferromagnetism of Ni-doped ZnO thin films

Yu, Wenyan; Yang, Liang; Teng, Xinying; Zhang, J. C.; Zhang, Z. C.; Zhang, L.; Fu, Guangsheng

doi:10.1063/1.2903524

Cited by 69 publications

(24 citation statements)

References 20 publications

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“…observed room temperature ferromagnetism in ZnO films doped with 1%, 3%, and 5% of Ni [13]. On the other hand, Jin et al found no indication of ferromagnetism in Zn 1-x [16].…”

Section: Introductionmentioning

confidence: 93%

Structural, optical and magnetic properties of Ni-doped ZnO micro-rods grown by the spray pyrolysis method

Yılmaz

McGlynn

Bacaksız

et al. 2012

Chemical Physics Letters

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Undoped and Ni-doped ZnO micro-rod arrays were successfully synthesized by the spray pyrolysis method on glass substrates. Analysis of the samples with x-ray diffraction and scanning electron microscopy showed that these micro-rod arrays had a polycrystalline wurtzite structure with a highly c-axis preferred orientation. Photoluminescence studies at both 300 K and 10 K show that the incorporation of nickel leads to a relative increase in the visible blue light band intensity. Magnetic measurements indicated that Ni-doped ZnO samples exhibit ferromagnetic behavior at room temperature, which is possibly related to the presence of point defects.

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“…observed room temperature ferromagnetism in ZnO films doped with 1%, 3%, and 5% of Ni [13]. On the other hand, Jin et al found no indication of ferromagnetism in Zn 1-x [16].…”

Section: Introductionmentioning

confidence: 93%

Structural, optical and magnetic properties of Ni-doped ZnO micro-rods grown by the spray pyrolysis method

Yılmaz

McGlynn

Bacaksız

et al. 2012

Chemical Physics Letters

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“…11,12 However, there are still many inconsistencies and controversies with respect to the origin of the magnetic properties described for Ni-doped ZnO in the literature. For instance, some authors 10,13 observed in their Nidoped ZnO films that the saturation magnetic moments decrease with the Ni-doping concentration. Meanwhile, Thota et al 14 found that the magnetization value of Zn 1−x Ni x O / ZnO ͑0.01Յ x Յ 0.163͒ bilayers increases with an increase in the nickel content.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence studies on structural defects and room temperature ferromagnetism in Ni and Ni–H doped ZnO nanoparticles

Tong

Chen

Han

et al. 2010

Journal of Applied Physics

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We explore the effects of hydrogenated annealing on the crystal structure, room temperature ferromagnetism (RT-FM) and photoluminescence (PL) properties of Ni-doped ZnO (Zn1−xNixO, x=0.0 to 0.2) nanoparticles prepared by a sol-gel method. The x-ray photoelectron spectra and x-ray diffraction data provide evidence that Ni has been incorporated into the wurtzite ZnO lattice as Ni2+ ions substituting for Zn2+ ions at x≤0.05. A secondary phase of NiO type begins to form inside ZnO when x>0.05 and segregates from ZnO host lattice at x=0.2, leading to a large variation in the lattice constants of ZnO. The magnetization measurements show that the saturation magnetization (Ms) increases with increasing Ni concentration in the single-phase Zn1−xNixO (x≤0.05) nanoparticles. The secondary phase formation reduces the magnetization of Zn1−xNixO (x=0.1 and 0.15), while the segregation of NiO from the ZnO lattice at x=0.2 is accompanied by a large increase in Ms again. The PL measurements show that the UV emission intensity of single-phase Zn1−xNixO (x≤0.05) nanoparticles increases with a blueshift in the UV emission line when the Ni concentration increases, while the dominant green emission intensity decreases with increasing Ni dopant. The PL data strongly suggest that the FM in single-phase Zn1−xNixO (x≤0.05) nanoparticles is intrinsically correlated with a doping induced increase in the electron concentration in the conduction band of Ni-doped ZnO. After H2-annealing, the single-phase Zn1−xNixO:H (x≤0.05) nanoparticles show increases in both coercivity and saturation magnetization. The PL and diffuse reflectance spectra suggest that hydrogen-related shallow donors and an improved sample quality may be responsible for the H2-annealing induced enhancement of the RT-FM. The obvious correlation between FM and carrier concentration in Ni and Ni–H doped ZnO points towards a mechanism of carrier-mediated FM for Ni-doped ZnO diluted magnetic semiconductors.

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“…3. The reduction in the average grain size generates more interface states, which in turn trap the conduction electrons [9,24] and do not allow them to get activated easily in the conduction band as compared to A1 and A2. The same holds for the variation of activation energies calculated in case of thermionic emission of electrons from grain boundary barriers present in all the films.…”

Section: Electrical Conduction Mechanism At Low Temperature Rangementioning

confidence: 98%

Correlation between electrical transport, microstructure and room temperature ferromagnetism in 200 keV Ni2+ ion implanted zinc oxide (ZnO) thin films

et al. 2012

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We report variable temperature resistivity measurements and mechanisms related to electrical conduction in 200 keV Ni 2+ ion implanted ZnO thin films deposited by vapor phase transport. The dc electrical resistivity versus temperature curves show that all polycrystalline ZnO films are semiconducting in nature. In the room temperature range they exhibit band conduction and conduction due to thermionic emission of electrons from grain boundaries present in the polycrystalline films. In the low temperature range, nearest neighbor hopping (NNH) and variable range hopping (VRH) conduction are observed. The detailed conduction mechanism of these films and the effects of grain boundary (GB) barriers on the electrical conduction process are discussed. An attempt is made to correlate electrical conduction behavior and previously observed room temperature ferromagnetism of these films.

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Influence of structure characteristics on room temperature ferromagnetism of Ni-doped ZnO thin films

Cited by 69 publications

References 20 publications

Structural, optical and magnetic properties of Ni-doped ZnO micro-rods grown by the spray pyrolysis method

Structural, optical and magnetic properties of Ni-doped ZnO micro-rods grown by the spray pyrolysis method

Photoluminescence studies on structural defects and room temperature ferromagnetism in Ni and Ni–H doped ZnO nanoparticles

Correlation between electrical transport, microstructure and room temperature ferromagnetism in 200 keV Ni2+ ion implanted zinc oxide (ZnO) thin films

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