Element Specific Versus Integral Structural and Magnetic Properties of Co:ZnO and Gd:GaN Probed with Hard X-ray Absorption Spectroscopy

Ney, A.

doi:10.3390/ma3063565

Cited by 19 publications

(9 citation statements)

References 157 publications

(306 reference statements)

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“…It has been recently refined by a more detailed analysis, that the element specific magnetization curves published earlier 6 can be best fitted with a small fraction of 15% which behaves super paramagnetically, i.e., Langevin‐like and is therefore in line with our interpretation of the EPR data as described in Ref. 4. For the sake of completeness we provide the plot of Fig.…”

supporting

confidence: 70%

“…Our original interpretation of Res1 and Res2 (In fact, unlike inferred by Gehlhoff et al we have never discussed any Res3) as being caused by Gd and/or GdN nanoclusters cannot be dismissed since the respective EPR spectra were not simulated by Gehlhoff et al We admit that this task would be even more difficult to do since it relies on even more, partially unknown, parameters. On the other hand, complementary experimental evidence as most recently discussed 4, makes it likely that the onset of phase separation occurs in this sample. We think that while Fig.…”

mentioning

confidence: 53%

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Reply to “Comment on 'Paramagnetic and ferromagnetic resonance studies on dilute magnetic semiconductors based on GaN' ” [Phys. Status Solidi A 205, 1872 (2008)]

Kammermeier

Ney

Wieck

2011

Physica Status Solidi (a)

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In a comment by Gehlhoff et al. on our work on “Paramagnetic and ferromagnetic resonance studies on dilute magnetic semiconductors based on GaN” [Phys. Status Solidi A 205, 1872 (2008)] the authors claim a contradictory explanation of angular dependent magnetic resonance measurements. Here we discuss their – solely based on computer simulations – claims. We show that an interpretation limited on magnetic impurities can hardly be used to explain the complex magnetic behavior.

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confidence: 70%

mentioning

confidence: 53%

Reply to “Comment on 'Paramagnetic and ferromagnetic resonance studies on dilute magnetic semiconductors based on GaN' ” [Phys. Status Solidi A 205, 1872 (2008)]

Kammermeier

Ney

Wieck

2011

Physica Status Solidi (a)

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“…This simulated spectrum is then superimposed with the simulated spectrum of Co-doped ZnO (green line) in the same way as was reported in Ref. [22]. The superimposed spectrum is plotted as a thick red line in Fig.…”

Section: Resultsmentioning

confidence: 99%

Local structure and magnetism of Co3+ in wurtzite Co:ZnO

et al. 2017

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The structural and magnetic properties of 30% and 50% Co-doped ZnO have been investigated in order to determine the influence of the presence of Co 3+ as a potential p-type dopant. For 30% doping, Co 3+ could be stabilized in the wurtzite lattice of ZnO without phase separation by providing high oxygen partial pressures during growth. At 50% Co concentration, the crystal lattice destabilizes. X-ray absorption spectroscopy and simulations are used to substantiate the valence and local structure of Co 3+ . Integral and element selective magnetometry reveals uncompensated antiferromagnetism of the Co atoms irrespective of being present as Co 2+ or Co 3+ .

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“…Gd‐implanted GaN has attracted strong interest as a promising candidate for room temperature spin injectors after experimental reports on ferromagnetism with a Curie temperature far above room temperature . The existence and possible microscopic origins of ferromagnetism in Gd:GaN are, however, controversially discussed both from experimental and theoretical side . The ability to efficiently polarize conduction band electrons has also not yet been demonstrated though it is the prerequisite for an application as a spin injector.…”

Section: Spin Dynamics In Ion‐implanted Ganmentioning

confidence: 99%

Electron spin dynamics in GaN

Rudolph

Buß

Hägele

2014

Physica Status Solidi (b)

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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Gallium nitride is a promising material system for spintronics, offering long spin relaxation times and prospects for room-temperature ferromagnetism. We review the electron spin dynamics in bulk GaN. Time-resolved magneto-optical studies of both the wurtzite and the cubic phase of GaN show the dominance of Dyakonov-Perel (DP) relaxation for free conduction band electrons. Spin relaxation in the wurtzite phase is characterized by an intrinsic spin relaxation anisotropy and the limitation of spin lifetimes by a strong Rashba term. Spin lifetimes are strongly enhanced in cubic GaN, where only a weak Dresselhaus term contributes to DP relaxation. Ion-implanted wurtzite GaN shows a strong increase of electron spin lifetimes for increasing implantation dose, caused by increasing localization of carriers. The spin dynamics of conduction band electrons in Gd-implanted GaN as a candidate for a room-temperature ferromagnetic semiconductor is also only governed by localization effects and does not show signs of an efficient exchange coupling between the electrons and the magnetic Gd ions.1 Introduction Spintronics as the novel spin-based semiconductor electronics has been an intense and fruitful field of research in the last years, leading to the discovery and detailed understanding of numerous spin effects [1][2][3][4][5]. In addition, a plethora of possible applications including, e.g., the famous spin transistor [6] or spin optoelectronic devices [7][8][9], has been proposed. However, for the realization of the proposed concepts challenging requirements are imposed on the underlying semiconductor materials, like, e.g., very long spin lifetimes or ferromagnetic behavior with Curie temperatures above room temperature. These challenges have triggered intense research on optimized structures and new materials. In particular, GaN has attracted strong interest as it promises to combine fascinating properties, ranging from weak spin-orbit coupling due to its light constituting elements over high-temperature ferromagnetism upon doping with rare earth ions [10] up to its good optoelectronic properties [11] and its well established use in the semiconductor industry [12]. In addition, GaN is a highly instructive model system for the influence of crystal symmetry on the electron spin dynamics as besides the thermodynamically stable wurtzite phase also the metastable cubic phase can be prepared [13]. While the spin dynamics in the dilute nitrides GaNAs and GaInNAs [14][15][16][17][18], and of holes [19] and especially excitons in GaN [20][21][22][23]

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Element Specific Versus Integral Structural and Magnetic Properties of Co:ZnO and Gd:GaN Probed with Hard X-ray Absorption Spectroscopy

Cited by 19 publications

References 157 publications

Reply to “Comment on 'Paramagnetic and ferromagnetic resonance studies on dilute magnetic semiconductors based on GaN' ” [Phys. Status Solidi A 205, 1872 (2008)]

Reply to “Comment on 'Paramagnetic and ferromagnetic resonance studies on dilute magnetic semiconductors based on GaN' ” [Phys. Status Solidi A 205, 1872 (2008)]

Local structure and magnetism of Co3+ in wurtzite Co:ZnO

Electron spin dynamics in GaN

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