Extrinsic origin of ferromagnetism in ZnO and Zn0.9Co0.1O magnetic semiconductor films prepared by sol-gel technique

Belghazi, Y.; Schmerber, G.; Colis, S.; Rehspringer, Jean‐Luc; Dinia, A.; Berrada, A.

doi:10.1063/1.2355462

Cited by 99 publications

(56 citation statements)

References 29 publications

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“…Presently, there is no consensus on the exact exchange mechanism in such WBG-DMSs [6]. The ferromagnetism in ZnO has been attributed to defect-induced [7] or defect-mediated magnetism [8][9][10][11][12]. Furthermore, a density functional theory (DFT) study of Eu-doped ZnO reported ferromagnetic coupling when the RE atoms were in nearest neighbor positions [13].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

Roqan¹,

Aravindh²,

Singaravelu³

2016

Magnetic Materials

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The magnetic properties of Gd-doped ZnO films and nanostructures are important to the development of next-generation spintronic devices. Here, we elucidate the significant role played by Gd-oxygen-deficiency defects in mediating/inducing ferromagnetic coupling in in situ Gd-doped ZnO thin films deposited at low oxygen pressure by pulsed laser deposition (PLD). Samples deposited at higher oxygen pressures exhibited diamagnetic responses. Vacuum annealing was used on these diamagnetic samples (grown at a relatively high oxygen pressures) to create oxygendeficiency defects with the aim of demonstrating reproducibility of room-temperature ferromagnetism (RTFM). Samples annealed at oxygen environment exhibited superparamagnetism and blocking-temperature effects. The samples possessed secondary phases; Gd segregation led to superparamagnetism. Theoretical studies showed a shift of the 4f level of Gd to the conduction band minimum (CBM) in Gd-doped ZnO nanowires, which led to an overlap with the Fermi level, resulting in strong exchange coupling and consequently RTFM.

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Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

Roqan¹,

Aravindh²,

Singaravelu³

2016

Magnetic Materials

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“…However, the inconsistent experimental results raise a new problem of explaining the mechanism of ferromagnetism in TM-doped ZnO. Moreover, it is difficult to exclude the possibility that the ferromagnetism might be brought by a secondary phase of TM oxides or TM dopant clusters [13,14,15]. Consequently, many researchers turned their attention to non-TM doped ZnO and tried to provide undisputed intrinsic DMS.…”

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confidence: 99%

Intrinsic room temperature ferromagnetism in boron-doped ZnO

Yang

et al. 2010

Applied Physics Letters

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We report room temperature ferromagnetism in boron-doped ZnO both experimentally and theoretically. The single phase Zn 1-x B x O films deposited under high oxygen pressure by pulsed-laser deposition show ferromagnetic behavior at room temperature. The saturation magnetization increases monotonously from 0 to 1.5 emu/cm 3 with the increasing of B componentx from 0 to 6.8%. The first-principles calculations based on density functional theory demonstrate that the ferromagnetism in B-doped ZnO originates from the induced magnetic moments of oxygen atoms in the nearest neighbor sites to the B-Zn vacancy pair. The calculated total magnetic moment increasing tendency with B component is well consistent with experiments. * To whom correspondence should be addressed. Email: yjiang@ustb.edu.cn 1 Dilute magnetic semiconductors (DMS) are promising candidates for spintronics devices due to their peculiar magnetic and semiconductor properties. In recent years, researchers have made great efforts to design and fabricate DMS, especially those with Curie temperature (T C ) above room temperature. Among all DMS candidates, ZnO has attracted wide interest, since it is predicted to be an ideal room-temperature DMS by Dietl et al. [1]. The magnetic moments of oxygen atoms around Zn vacancy are confirmed to be an origin of the ferromagnetic (FM) property in pure ZnO system [ 2 , 3 ]. However, the density of Zn vacancy is sensitive to experimental conditions and difficult to be controlled. Transition metal (TM) doping is a traditional method to obtain room temperature ferromagnetism in ZnO system [4,5,6,7,8,9,10,11,12]. However, the inconsistent experimental results raise a new problem of explaining the mechanism of ferromagnetism in TM-doped ZnO. Moreover, it is difficult to exclude the possibility that the ferromagnetism might be brought by a secondary phase of TM oxides or TM dopant clusters [13,14,15]. Consequently, many researchers turned their attention to non-TM doped ZnO and tried to provide undisputed intrinsic DMS. Pan et al. [16] theoretically predicted and experimentally realized room temperature ferromagnetism in carbon-doped ZnO films. A further work by Peng et al. [17] demonstrated the hole-induced mechanism in p-group element-doped FM ZnO system, which opens a new way for studying non-TM doped ZnO DMS.In this letter, we report our experimental study on 2p-group element B-doped ZnO system. First-principles calculations based on the density functional theory justify the intrinsic ferromagnetism in the system is induced by oxygen atoms in the nearest neighbor sites to the B-Zn vacancy pair, which is quite different from the origin of the ferromagnetism in carbon-doped ZnO.All the B-doped ZnO thin films were grown by pulsed-laser deposition (PLD) using a KrF 2 excimer laser operating at 300 mJ/pluse and 10 Hz. The targets were prepared by sintering mixed ZnO (99.99%) The most possible site for B should be tetrahedral or octahedral interstice in ZnO, due to the small radius of B. According to our calculation,...

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“…Note that SQUID magnetometry is an integral method, which measures the total magnetic response from the sample, including substrate and possible contaminations from previous processing [43,44]. On the other hand, conversion electron Mössbauer spectroscopy (CEMS) is an element specific method, which was used to investigate the 57 Fe lattice sites, electronic configuration and corresponding magnetic hyperfine fields.…”

Section: Experimental Methodsmentioning

confidence: 99%

Ferromagnetic transition metal implanted ZnO: A diluted magnetic semiconductor?

Zhou

Potzger

et al. 2009

Vacuum

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Recently theoretical works predict that some semiconductors (e.g. ZnO) doped with magnetic ions are diluted magnetic semiconductors (DMS). In DMS magnetic ions substitute cation sites of the host semiconductor and are coupled by free carriers resulting in ferromagnetism. One of the main obstacles in creating DMS materials is the formation of secondary phases because of the solid-solubility limit of magnetic ions in semiconductor host. In our study transition metal ions were implanted into ZnO single crystals with the peak concentrations of 0.5-10 at.%. We established a correlation between structural and magnetic properties. By synchrotron radiation X-ray diffraction (XRD) secondary phases

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Extrinsic origin of ferromagnetism in ZnO and Zn0.9Co0.1O magnetic semiconductor films prepared by sol-gel technique

Cited by 99 publications

References 29 publications

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

Intrinsic room temperature ferromagnetism in boron-doped ZnO

Ferromagnetic transition metal implanted ZnO: A diluted magnetic semiconductor?

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