Carrier-induced ferromagnetism in n-type ZnMnAlO and ZnCoAlO thin films at room temperature

Xu, Xin; Blythe, H. J.; Ziese, M.; Behan, A.J.; Neal, James R.; Mokhtari, Abbas; Ibrahim, Ragheed M.; Fox, A. M.; Gehring, G. A.

doi:10.1088/1367-2630/8/8/135

Cited by 146 publications

(90 citation statements)

References 25 publications

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“…In samples that are dominated by n-type Zn interstitials and oxygen vacancies the magnetization decreases sharply as oxygen is added. 4 In contrast, in the films grown from Co metal precursors that have Zn vacancies, we found the largest RT magnetization in films grown at the highest pressure, which also had the largest grain sizes. The results indicate that the use of Co-metal as the precursor for the target is beneficial for the growth of films that do not contain metallic Co but are strongly magnetic.…”

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confidence: 61%

“…These include the stoichiometric transfer of material from the target to the film and the control of oxygenation during the film growth. A general trend for Co-doped ZnO has been to find that a deficiency of oxygen in the growth chamber enhances the ferromagnetism through the formation of donor states [4][5][6][7] and that annealing films in air or oxygen quenches any magnetization [8][9][10] although there are also a few conflicting results in which magnetism is observed in ZnO oxygenated films with and without doping with Co. 11,12 The role of metallic Co precipitates is less clear, with some authors claiming that they are responsible for all of the observed magnetic properties [13][14][15] ; however, other authors have identified ferromagnetic phases in ZnCoO films that lack any metallic component. 16,17 The PLD growth of ZnCoO starts from a target that has been made to the desired composition by a solid-state reaction of a Co-containing compound and zinc oxide.…”

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confidence: 99%

“…In these n-type samples, the magnetization decreases sharply as oxygen is added. 4,[8][9][10] An undoped ZnO film has Zn interstitials and O vacancies when oxygen deficient and Zn vacancies and O interstitials when grown with excess oxygen. The magnetism in the films with excess oxygen is due to Zn vacancies.…”

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confidence: 99%

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Advantageous use of metallic cobalt in the target for pulsed laser deposition of cobalt-doped ZnO films

Ying

Blythe

Dizayee

et al. 2016

Applied Physics Letters

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We investigate the magnetic properties of ZnCoO thin films grown by pulsed laser deposition (PLD) from targets made containing metallic Co or CoO precursors instead of the usual Co 3 O 4 . We find that the films grown from metallic Co precursors in an oxygen rich environment contain negligible amounts of Co metal, and have a large magnetization at room temperature. Structural analysis by X-ray diffraction and magneto-optical measurements indicate that the enhanced magnetism is due, in part, from Zn vacancies that partially compensate the naturally occurring n-type defects. We conclude that strongly magnetic films of Zn 0.95 Co 0.05 O that do not contain metallic cobalt can be grown by PLD from Co-metal-precursor targets if the films are grown in an oxygen atmosphere.

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confidence: 99%

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Advantageous use of metallic cobalt in the target for pulsed laser deposition of cobalt-doped ZnO films

Ying

Blythe

Dizayee

et al. 2016

Applied Physics Letters

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“…In contrast, the CTF model predicts that the moments are entirely localized on itinerant carriers confined to small regions possibly grain boundaries. 16 Although each model has its merits in certain aspects, [17][18][19][20][21][22][23][24][25][26] a complete understanding of the ferromagnetic behavior in oxide DMSs still calls for more microscopic insights into the defect structure, transport property, and moment distribution in these systems.…”

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confidence: 99%

Carrier-mediated nonlocal ferromagnetic coupling between local magnetic polarons in Fe-doped In2O3and Co-doped ZnO

Jiang

Fan

et al. 2011

Phys. Rev. B

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The combined roles of oxygen vacancy and electron doping in mediating local and nonlocal magnetic ordering of Fe doped in In 2 O 3 and Co doped in ZnO have been investigated within first-principles density functional theory. We first show theoretically that two magnetic dopants can be stabilized energetically around an oxygen vacancy, and are ferromagnetically coupled to form a local magnetic polaron.Furthermore, electron doping plays the elegant dual role of further enhancing the ferromagnetic stability of a local polaron, and more crucially, mediating the nonlocal 2 magnetic coupling between two polarons. We finally provide experimental evidence supporting these strong predictions.

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“…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.…”

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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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Carrier-induced ferromagnetism in n-type ZnMnAlO and ZnCoAlO thin films at room temperature

Cited by 146 publications

References 25 publications

Advantageous use of metallic cobalt in the target for pulsed laser deposition of cobalt-doped ZnO films

Advantageous use of metallic cobalt in the target for pulsed laser deposition of cobalt-doped ZnO films

Carrier-mediated nonlocal ferromagnetic coupling between local magnetic polarons in Fe-doped In2O3and Co-doped ZnO

Intrinsic room temperature ferromagnetism in boron-doped ZnO

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