Doping concentration dependence of room-temperature ferromagnetism for Ni-doped ZnO thin films prepared by pulsed-laser deposition

Liu, Xiaoxue; Sun, Linlin; Cheng, Wen-Chieh; Ma, Xiaoqing; Shi, Wangzhou

doi:10.1063/1.2170420

Cited by 154 publications

(58 citation statements)

References 18 publications

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“…However, these studies indicate that ferromagnetism strongly depends on the methods and conditions used in their preparation. For example, Liu et al reported room temperature ferromagnetism in Ni-doped ZnO thin films grown by pulsed-laser deposition [11]; above 30 K superparamagnetic behavior was obtained by Bodker et al [12]. Yu et al…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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%

“…[4][5][6] Recently, some experimental evidence for a high-temperature ferromagnetic state in the Nidoped ZnO system has been reported, in consistency with theoretical predictions. 7,8 The experimental observations are based on Ni-doped ZnO films 9,10 and aggregated nanocrystals of Ni 2+ : ZnO. 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.…”

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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“…Among the different types of wide-band-gap semiconductors ZnO, with a direct band gap of 3.37 eV and a large exciton binding energy of 60 meV, has become one of the most important functional semiconducting materials for electro-optical devices like UV light emitters [4], piezoelectric transducers [5] and gas sensors [6]. Doping ZnO with transition metals has received considerable interest due to its room temperature ferromagnetism [7][8][9]. In 2000, Dietl et al [10] predicted theoretically that Mn doped ZnO and GaN would be ferromagnetic at room temperature and would therefore be suitable for applications in spintronics.…”

Section: Introductionmentioning

confidence: 99%

Structural, optical and magnetic properties of Cr doped ZnO microrods prepared by spray pyrolysis method

Yılmaz

Parlak

Özcan

et al. 2011

Applied Surface Science

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A series of Cr-doped ZnO micro-rod arrays were fabricated by a spray pyrolysis method. X-ray diffraction patterns of the samples showed that the undoped and Cr-doped ZnO microrods exhibit hexagonal crystal structure. Surface morphology analysis of the samples has revealed that pure ZnO sample has a hexagonal microrod morphology.From X-ray photoelectron spectroscopy studies, the Cr 2p3/2 binding energy is found to be 577.34 eV indicating that the electron binding energy of the Cr in ZnO is almost the same as the binding energy of Cr 3+ states in Cr 2 O 3 .The optical band gap E g decreases slightly from 3.26 to 3.15 eV with the increase of actual Cr content from x = 0.00 to 4.63 at % in ZnO. Photoluminescence studies at 10 K show that the incorporation of chromium leads to a relative increase of deep level band intensity. It was also observed that Cr doped samples clearly showed ferromagnetic behavior; however, 2.49 % Cr doped ZnO showed remnant magnetization higher than that of 1.07 % and 4.63 % Cr doped samples, while 4.63 % Cr doped ZnO samples had a coercive field higher than the other dopings.

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Doping concentration dependence of room-temperature ferromagnetism for Ni-doped ZnO thin films prepared by pulsed-laser deposition

Cited by 154 publications

References 18 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

Structural, optical and magnetic properties of Cr doped ZnO microrods prepared by spray pyrolysis method

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