Magnetism in dilute magnetic oxide thin films based on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Sn</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>

Fitzgerald, C. B.; Venkatesan, M.; Dorneles, L. S.; Gunning, Robert D.; Stamenov, Plamen; Coey, J. M. D.; Stampe, P. A.; Kennedy, R. J.; Moreira, Eduardo Ceretta; Sias, U.S.

doi:10.1103/physrevb.74.115307

Cited by 263 publications

(134 citation statements)

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“…7 Concurrently, with the recent pursuit for spintronicsrelated technology, 15,16 magnetic oxide semiconductors are receiving much attention as potential candidate materials of interest and promoting the rather new and exciting field of "oxide spintronics." [17][18][19][20][21][22][23][24] Oxides, unlike the III-V compounds, tend to exhibit a much higher Curie temperature when doped and can accommodate a much higher doping concentration of magnetic impurity atoms. 24 More interestingly, some oxides that are traditionally thought to be "nonmagnetic" have recently been shown to exhibit relatively large intrinsic magnetic moments, i.e., without the intentional introduction of magnetic dopants.…”

Section: Introductionmentioning

confidence: 99%

Native defect-induced multifarious magnetism in nonstoichiometric cuprous oxide: First-principles study of bulk and surface properties ofCu2−δO

et al. 2009

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Native defects in cuprous oxide Cu 2 O are investigated by using first-principles calculations based on density-functional theory. Considering the formation of copper and oxygen vacancies, antisites and interstitials, and a copper split-vacancy complex defect, we analyze the electronic structure and calculate their respective formation energies as a function of the change in Fermi level under both copper-rich and oxygen-rich conditions. We find that, under both growth conditions, the defect with the lowest formation energy is the simple copper vacancy, followed by the copper split-vacancy complex. Both low-energy copper defects produce hole states at the top of the valence band, largely accounting for the p-type conductivity in this material. In spite of the creation of dangling bonds at the nearest-neighbor O atoms, these copper defects are found to be spin neutral. Under oxygen-rich conditions, oxygen interstitials have low formation energies and are found to exhibit a ferromagnetic ordering with a total magnetic moment of 1.38 B and 1.36 B at the octahedral and tetrahedral sites, respectively. Considering the possibility of native defect formation at the surface of this material, we investigate the relative stability of both low-and high-index copper-oxide surfaces by comparing their surface free energies as a function of the change in oxygen chemical potential. Using the technique of ab initio atomistic thermodynamics, we then correlate the dependence of the calculated Gibbs free-surface energy as a function of oxygen pressure and temperature via the oxygen chemical potential. We identify two lowenergy surface structures, namely, Cu 2 O͑110͒ : CuO and Cu 2 O͑111͒-Cu CUS , with the former marginally more stable for oxygen-rich conditions and the latter more stable for oxygen-lean ͑or copper-rich͒ conditions. Cu 2 O͑110͒ : CuO is calculated to be nonmagnetic and Cu 2 O͑111͒-Cu CUS is calculated to be a ferromagnetic ordering, with a total magnetic moment of 0.91 B per defect. With the results for both bulk and surface native defects, we find that under oxygen-lean conditions, a ferromagnetic behavior could be attributed mainly to copper vacancy formation in the ͑111͒ surface of Cu 2 O while under oxygen-rich conditions, low-energy bulk oxygen interstitial defects induce a ferromagnetic character in the same material. This highlights the complementary role of bulk and surface native magnetic defects under different pressure and temperature conditions, especially at the nanoparticle scale where surface properties dominate.

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Section: Introductionmentioning

confidence: 99%

Native defect-induced multifarious magnetism in nonstoichiometric cuprous oxide: First-principles study of bulk and surface properties ofCu2−δO

et al. 2009

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“…[1][2][3] SnO 2 has been extensively researched as a dilute magnetic semiconductor since Dietl 4 predicted room temperature ferromagnetism (RTFM) in Mn-doped ZnO 4 , and several theoretical models propose to explain observations of RTFM in SnO 2 . [5][6][7] Recent computational work predicts RTFM in SnO 2 due to nitrogen substitution 8 , surface carbon 9 , or non-magnetic dopants. 10,11 Raman et al proposed RTFM due to tin vacancies 12 , but V sn is not considered thermodynamically favorable.…”

Section: Introductionmentioning

confidence: 99%

Size, surface structure, and doping effects on ferromagnetism in SnO2

Alanko

Thurber

Hanna

et al. 2012

Journal of Applied Physics

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The effects of crystallite size, surface structure, and dopants on the magnetic properties of semiconducting oxides are highly controversial. In this work, Fe:SnO 2 nanoparticles were prepared by four wet-chemical methods, with Fe concentration varying from 0-20%. Samples were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). Analysis confirmed pure single-phase cassiterite with a crystallite size of 2.6 ± 0.1 nm that decreased with increasing Fe%. Fe concentration was confirmed from XPS studies, with Fe ions in the 3+ oxidation state. Pure SnO 2 showed highly reproducible weak magnetization that varied significantly with synthesis method. Interestingly, doping SnO 2 with Fe<2.5% produced enhanced magnetic moments in all syntheses; the maximum of 1.6x10 -4 µ B /Fe ion at 0.1% Fe doping was much larger than the 2.6x10 -6 µ B /Fe ion of pure Fe oxide nanoparticles synthesized under similar conditions. At Fe≥2.5%, the magnetic moment was significantly reduced. This work shows that (i) pure SnO 2 can produce an intrinsic ferromagnetic behavior that varies with differences in surface structure, (ii) very low Fe doping results in high magnetic moments, (iii) higher Fe doping reduces magnetic moment and destroys ferromagnetism, and (iv) there is an interesting correlation between changes in magnetic moment, band gap, and lattice parameters. These results support the possibility that the observed ferromagnetism in SnO 2 might be influenced by modification of the electronic structure by dopant, size, and surface structure. Introduction:

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“…[6][7][8][9][10][11][12][13][14] There have been several proposed explanations for the room temperature ferromagnetism of DMO such as overlapping bound magnetic polarons with oxygen vacancies, 4 superexchange between magnetic impurities and oxygen vacancies, 15 carrier-mediated RKKY exchange, 16 F-center exchange, 17 d 0 ferromagnetism due to lattice or bond defects, 18 and some sort of structural defects other than charge-compensating oxygen vacancies. 19 Although these observations and models suggest importance of intrinsic defects to activate ferromagnetism in DMO, there has been few direct observation of the defects.…”

Section: -10mentioning

confidence: 99%