Ferromagnetism induced by intrinsic defects and carbon substitution in single-walled ZnO nanotube

Gao, Feng; Hu, Jifan; Wang, Jihua; Yang, Chuan‐Lu; Qin, Hongwei

doi:10.1016/j.cplett.2010.01.069

Cited by 15 publications

(3 citation statements)

References 45 publications

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“…The TiO 2 (hereafter referring to the anatase structure exclusively) (101) surfaces were modeled by vacuum slabs. According to our previous computational results [19] and some references [20,21], we have selected a slab of Ti 24 O 48 (TO) with surface area of 11.15 × 7.55Å 2 and slab thickness of 3 layers (see Figure 1(a)). The surface species, namely, the bridging two-fold coordinated oxygen atom (O 2C ), three types of three-fold coordinated oxygen atom…”

Section: Modelsmentioning

confidence: 99%

Electronic Structures of S/C-Doped TiO₂Anatase (101) Surface: First-Principles Calculations

Chen

Liu

et al. 2014

International Journal of Photoenergy

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The electronic structures of sulfur (S) or carbon (C)-doped TiO2anatase (101) surfaces have been investigated by density functional theory (DFT) plane-wave pseudopotential method. The general gradient approximation (GGA) +U(Hubbard coefficient) method has been adopted to describe the exchange-correlation effects. All the possible doping situations, including S/C dopants at lattice oxygen (O) sites (anion doping), S/C dopants at titanium (Ti) sites (cation doping), and the coexisting of anion and cation doping, were studied. By comparing the formation energies, it was found that the complex of anion and cation doping configuration forms easily in the most range of O chemical potential for both S and C doping. The calculated density of states for various S/C doping systems shows that the synergistic effects of S impurities at lattice O and Ti sites lead a sharp band gap narrowing of 1.35 eV for S-doped system comparing with the pure TiO2system.

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Section: Modelsmentioning

confidence: 99%

Electronic Structures of S/C-Doped TiO₂Anatase (101) Surface: First-Principles Calculations

Chen

Liu

et al. 2014

International Journal of Photoenergy

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“…ZnO-based dilute magnetic semiconductors have been extensively studied due to the predication of ferromagnetism above room temperature. [7][8][9][10][11] Subsequently, ZnO d 0 ferromagnetism has been found to exist in undoped ZnO [12][13][14][15][16][17] or in ZnO doped with non-magnetic ions, such as H, [18][19][20] Li, 21,22 C, [23][24][25] and N. 26,27 Based on both theoretical and experimental considerations, many groups have proposed that the ferromagnetism in nominally undoped ZnO arises from intrinsic defects. These defects include oxygen vacancy, 13,15,28,29 zinc interstitial, 13,15,28,30 zinc vacancy, 12,14,21,31,32 and the defect complex of zinc vacancy and H interstitial, 20 as well as oxygen interstitial.…”

Section: Introductionmentioning

confidence: 99%

Tuning magnetism by biaxial strain in native ZnO

Peng

Wang

Cheng

et al. 2015

Phys. Chem. Chem. Phys.

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Magnetic ZnO, one of the most important diluted magnetic semiconductors (DMS), has attracted great scientific interest because of its possible technological applications in optomagnetic devices. Magnetism in this material is usually delicately tuned by the doping level, dislocations, and local structures. The rational control of magnetism in ZnO is a highly attractive approach for practical applications. Here, the tuning effect of biaxial strain on the d(0) magnetism of native imperfect ZnO is demonstrated through first-principles calculations. Our calculation results show that strain conditions have little effect on the defect formation energy of Zn and O vacancies in ZnO, but they do affect the magnetism significantly. For a cation vacancy, increasing the compressive strain will obviously decrease its magnetic moment, while tensile strain cannot change the moment, which remains constant at 2 μB. For a singly charged anion vacancy, however, the dependence of the magnetic moment on strain is opposite to that of the Zn vacancy. Furthermore, the ferromagnetic state is always present, irrespective of the strain type, for ZnO with two zinc vacancies, 2VZns. A large tensile strain is favorable for improving the Curie temperature and realizing room temperature ferromagnetism for ZnO-based native semiconductors. For ZnO with two singly charged oxygen vacancies, 2Vs, no ferromagnetic ordering can be observed. Our work points the way to the rational design of materials beyond ZnO with novel non-intrinsic functionality by simply tuning the strain in a thin film form.

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“…In this regard, investigation of defect-induced room-temperature (RT) ferromagnetism (FM) in ZnO-based semiconductor has been drawn immense attention to the scientists as an alternative approach to prepare new class of dilute magnetic semiconductors (DMS) , for modern spintronic and opto-spintronic technology. , The observation of unexpected RT FM in pure HfO 2 thin film has opened up a new challenge to explain the origin of magnetic moment without the presence of any d or f-orbital electrons. After that the experimental evidence of RTFM were also observed in case of different oxide thin films and nanostructures such as ZnO, SnO 2 , TiO 2 , In 2 O 3 , etc., in their purest phase − or even using dopant elements that are completely nonmagnetic. − The theoretical calculations performed in case of different oxides such as HfO 2 , CaO, SnO 2, and ZnO revealed that cation vacancies can induce a magnetic moment, which is found to be localized at the vacancy site, and the ferromagnetic ordering between these cation vacancies is energetically favorable when vacancy concentration reaches above a threshold concentration. Sundaresan et al have reported that FM is a universal property of oxide nanostructures where they have attributed oxygen vacancy ( V O ) defects for the origin of observed FM.…”

Section: Introductionmentioning

confidence: 99%

Influence of Film Thickness and Oxygen Partial Pressure on Cation-Defect-Induced Intrinsic Ferromagnetic Behavior in Luminescent p-Type Na-Doped ZnO Thin Films

Ghosh

Khan

Varma

et al. 2013

ACS Appl. Mater. Interfaces

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In this article, we have investigated the effect of oxygen partial pressure (PO2) and film thickness on defect-induced room-temperature (RT) ferromagnetism (FM) of highly c-axis orientated p-type Na-doped ZnO thin films fabricated by pulse laser deposition (PLD) technique. We have found that the substitution of Na at Zn site (NaZn) can be effective to stabilize intrinsic ferromagnetic (FM) ordering in ZnO thin films with Curie temperature (TC) as high as 509 K. The saturation magnetization (MS) is found to decrease gradually with the increase in thickness of the films, whereas an increase in "MS" is observed with the increase in PO2 of the PLD chamber. The enhancement of ferromagnetic signature with increasing PO2 excludes the possibility of oxygen vacancy (VO) defects for the magnetic origin in Na-doped ZnO films. On the other hand, remarkable enhancement in the green emission (IG) are observed in the photoluminescence (PL) spectroscopic measurements due to Na-doping and that indicates the stabilization of considerable amount of Zn vacancy (VZn)-type defects in Na-doped ZnO films. Correlating the results of PL and X-ray photoelectron spectroscopy (XPS) studies with magnetic measurements we have found that VZn and Na substitutional (NaZn) defects are responsible for the hole-mediated FM in Na-doped ZnO films, which might be an effective candidate for modern spintronic technology.

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Ferromagnetism induced by intrinsic defects and carbon substitution in single-walled ZnO nanotube

Cited by 15 publications

References 45 publications

Electronic Structures of S/C-Doped TiO₂Anatase (101) Surface: First-Principles Calculations

Electronic Structures of S/C-Doped TiO₂Anatase (101) Surface: First-Principles Calculations

Tuning magnetism by biaxial strain in native ZnO

Influence of Film Thickness and Oxygen Partial Pressure on Cation-Defect-Induced Intrinsic Ferromagnetic Behavior in Luminescent p-Type Na-Doped ZnO Thin Films

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Ferromagnetism induced by intrinsic defects and carbon substitution in single-walled ZnO nanotube

Cited by 15 publications

References 45 publications

Electronic Structures of S/C-Doped TiO2Anatase (101) Surface: First-Principles Calculations

Electronic Structures of S/C-Doped TiO2Anatase (101) Surface: First-Principles Calculations

Tuning magnetism by biaxial strain in native ZnO

Influence of Film Thickness and Oxygen Partial Pressure on Cation-Defect-Induced Intrinsic Ferromagnetic Behavior in Luminescent p-Type Na-Doped ZnO Thin Films

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Electronic Structures of S/C-Doped TiO₂Anatase (101) Surface: First-Principles Calculations

Electronic Structures of S/C-Doped TiO₂Anatase (101) Surface: First-Principles Calculations