Absence of Intrinsic Ferromagnetic Interactions of Isolated and Paired Co Dopant Atoms in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Zn</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Co</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mi mathvariant="normal">O</mml:mi></mml:math>with High Structural Perfection

Ney, A.; Ollefs, Katharina; Ye, S.; Kammermeier, T.; Ney, V.; Kaspar, Tiffany C.; Chambers, Scott A.; Wilhelm, F.; Рогалев, А.

doi:10.1103/physrevlett.100.157201

Cited by 220 publications

(155 citation statements)

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“…The oxidation state of Co is therefore inferred to be 2þ in Co:ZnO, 28 in agreement with our X-ray absorption measurements, suggesting that Co substitutes for Zn in the lattice uniformly. 13 Figure 5(a) shows that the O a/b ratio increases slightly on approaching the interface between the Co:ZnO layer and the Al 2 O 3 . Since these measurements have relatively large errors, a more sensitive approach was used involving measurements of the threshold energy of the O K-edge to follow the change in chemical environment across the interface, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

Kovács

Ney

Duchamp

et al. 2013

Journal of Applied Physics

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Room-temperature ferromagnetic Co-doped ZnO nanoneedle array prepared by pulsed laser deposition Appl. Phys. Lett. 87, 173119 (2005) We study planar defects in epitaxial Co:ZnO dilute magnetic semiconductor thin films deposited on c-plane sapphire (Al 2 O 3 ), as well as the Co:ZnO/Al 2 O 3 interface, using aberration-corrected transmission electron microscopy and electron energy-loss spectroscopy. Co:ZnO samples that were deposited using pulsed laser deposition and reactive magnetron sputtering are both found to contain extrinsic stacking faults, incoherent interface structures, and compositional variations within the first 3-4 Co:ZnO layers next to the Al 2 O 3 substrate. The stacking fault density is in the range of 10 17 cm À3 . We also measure the local lattice distortions around the stacking faults. It is shown that despite the relatively high density of planar defects, lattice distortions, and small compositional variation, the Co:ZnO films retain paramagnetic properties. V C 2013 AIP Publishing LLC.

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Section: Resultsmentioning

confidence: 99%

“…Thin epitaxial films of Co:ZnO were deposited onto cplane sapphire substrates using PLD 13,14 and RMS. 5 Careful pre-characterization using x-ray diffraction, XAS, XLD, XMCD, and SQUID has been performed before for the PLD-10 (Refs.…”

Section: Methodsmentioning

confidence: 99%

Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

Kovács

Ney

Duchamp

et al. 2013

Journal of Applied Physics

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“…Ney et al 53 have demonstrated that highly perfect Co-doped epitaxial films, for example, are purely paramagnetic, with cobalt occupying zinc sites and no sign of anything other than weak antiferromagnetic Co-O-Co nearest-neighbor superexchange. Droubay et al 54 show that Mn-doped epitaxial films are paramagnetic, with Mn substituting for Zn, and no moments on either oxygen or zinc.…”

Section: Resultsmentioning

confidence: 99%

Effects of Cu diffusion-doping on structural, optical, and magnetic properties of ZnO nanorod arrays grown by vapor phase transport method

Yılmaz¹,

McGlynn²,

Bacaksız³

et al. 2012

Journal of Applied Physics

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Realization of a 33 GHz phononic crystal fabricated in a freestanding membrane AIP Advances 1, 042001 (2011) Preparation of uncapped CdSe1xSx semiconducting nanocrystals by mechanical alloying J. Appl. Phys. 110, 124306 (2011) Formation mechanisms of spatially-directed zincblende gallium nitride nanocrystals J. Appl. Phys. 110, 124307 (2011) Surface modification of monocrystalline zinc oxide induced by high-density electronic excitation J. Appl. Phys. 110, 124310 (2011) Investigation of poly(o-anisidine)-SnO2 nanocomposites for fabrication of low temperature operative liquefied petroleum gas sensor J. Appl. Phys. 110, 124501 (2011) Additional information on J. Appl. Phys. Well-aligned ZnO nanorods were prepared by the vapor phase transport method on Si covered with a ZnO buffer layer. After the nanostructure growth, Cu was doped into the ZnO nanorods by diffusion at three different temperatures and for different times. Undoped and Cu diffusion-doped ZnO samples are highly textured, with the c axis of the wurtzite structure along the growth direction. The incorporation of Cu caused some slight changes in the nanorod alignment, although the wurtzite crystal structure was maintained. X-ray photoelectron spectroscopy measurements revealed that Cu ions were in a divalent state and substituted for the Zn 2þ ions of the ZnO matrix. Photoluminescence results at 10 K indicate that the incorporation of copper leads to a relative increase of Cu-related structured green band deep level intensity. Magnetic measurements revealed that both undoped and Cu diffusion-doped ZnO samples exhibited room temperature ferromagnetism. It was also found that bound magnetic polarons play an important role in the appearance of room temperature ferromagnetism in Cu diffusion-doped ZnO nanorods.

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“…11,12 and references therein) and confirmed by X-ray linear dichroism (XLD) measurements. 13 However, some observations do not completely conform to the scenario where all impurities occupy Zn substitutional sites in ZnO. X-ray absorption near-edge structure spectroscopy (XANES) 4,14 and X-ray photoelectron spectroscopy (XPS) 15 experiments have shown that Mn impurities can be incorporated in ZnO with charge states of up to 4+.…”

Section: Introductionmentioning

confidence: 97%

Mixed Zn and O substitution of Co and Mn in ZnO

et al. 2011

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The physical properties of an impurity atom in a semiconductor are primarily determined by the lattice site it occupies. In general, this occupancy can be correctly predicted based on chemical intuition, but not always. We report on one such exception in the dilute magnetic semiconductors (DMS) Co-and Mn-doped ZnO, experimentally determining the lattice location of Co and Mn using β − emission channeling from the decay of radioactive 61 Co and 56 Mn implanted at the ISOLDE facility at CERN. Surprisingly, in addition to the majority substituting for Zn, we find up to 18% (27%) of the Co (Mn) atoms in O sites, which is virtually unaffected by thermal annealing up to 900 • C. We discuss how this anion site configuration, which had never been considered before for any transition metal in any metal oxide material, may in fact have a low formation energy. This suggests a change in paradigm regarding transition metal incorporation in ZnO and possibly other oxides and wide-gap semiconductors.

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Absence of Intrinsic Ferromagnetic Interactions of Isolated and Paired Co Dopant Atoms inZn1−xCoxOwith High Structural Perfection

Cited by 220 publications

References 13 publications

Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

Defects in paramagnetic Co-doped ZnO films studied by transmission electron microscopy

Effects of Cu diffusion-doping on structural, optical, and magnetic properties of ZnO nanorod arrays grown by vapor phase transport method

Mixed Zn and O substitution of Co and Mn in ZnO

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