Electrical and magnetic properties of RE-doped ZnO thin films (RE = Gd, Nd)

Ungureanu, Mariana; Schmidt, Heidemarie; Xu, Qingyu; Wenckstern, Holger von; Spemann, D.; Hochmuth, H.; Lorenz, Michael; Grundmann, Marius

doi:10.1016/j.spmi.2007.04.022

Cited by 76 publications

(34 citation statements)

References 6 publications

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“…4(b)] confirms that there is no exchange interaction between the Gd ions, which is consistent with the previous reports. 43 The absence of ferromagnetism in Gd-doped ZnO is in contrast with the previous report of a strong ferromagnetic order in another rare-earth-doped oxide, i.e., Nd-doped ZnO nanowires. 44 To understand the band structure of Gd-doped ZnO, we carried out first-principles DFT calculations.…”

Section: Resultscontrasting

confidence: 90%

Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

Deng

Lin

et al. 2013

Phys. Rev. B

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As a long-lived theme in solid-state physics, the Kondo effect reflects the many-body physics involving the short-range Coulomb interactions between itinerant electrons and localized spins in metallic materials. Here we show that the Kondo effect is present in ZnO, a prototypical wide-band-gap oxide, doped with a rare-earth element (Gd). The localized 4f electrons of Gd ions do not produce remanent magnetism, but interact strongly with the host electrons, giving rise to a saturating resistance upturn and negative magnetoresistance at low temperatures. Furthermore, the Kondo temperature and resistance can be electrostatically modulated using electric-double-layer gating with liquid ionic electrolyte. Our experiments provide the experimental evidence of tunable Kondo effect in ZnO, underscoring the magnetic interactions between localized and itinerant electrons and the emergent transport behaviors in such doped wide-band-gap oxides.

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Section: Resultscontrasting

confidence: 90%

Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

Deng

Lin

et al. 2013

Phys. Rev. B

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“…This preference of the surface sites is in line with the experimental findings in which RE dopants accumulate on the surface of ZnO nanowires during in situ deposition. 11 We find that an isolated Gd atom incorporated in a Zn site exhibits a magnetic moment of about 6.87l B , for all Gd positions.…”

Section: Resultsmentioning

confidence: 71%

“…8 FM is observed experimentally in ZnO thin films 9,10 and ZnO nanostructures doped with RE elements, such as Eu, Nd, and Gd. 11,12 In several experiments on ZnO nanowires doped with Gd, huge magnetic moments (3278l B /Gd) were obtained, which is attributed to the exchange interaction between 4f and 6s electrons. 11 Nd-doped ZnO nanowire arrays exhibit stable RTFM with magnetic moments of 4.1l B /Nd.…”

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confidence: 99%

“…11,12 In several experiments on ZnO nanowires doped with Gd, huge magnetic moments (3278l B /Gd) were obtained, which is attributed to the exchange interaction between 4f and 6s electrons. 11 Nd-doped ZnO nanowire arrays exhibit stable RTFM with magnetic moments of 4.1l B /Nd. 12 Gd-implanted ZnO single crystals 13 showed saturation moments of up to 1.8l B /Gd and FM has also been reported in nano-crystalline ZnO doped with 3.5% Gd.…”

mentioning

confidence: 99%

“…However, the existing experimental results are controversial and depend strongly on the doping method and the defect type. [10][11][12]15 In addition, the mechanism and origin of the magnetic coupling are poorly understood. The few theoretical studies that have been conducted thus far deal with RE doping in bulk ZnO and do not elucidate the mechanisms responsible for RTFM in Gd-doped wurtzite ZnO nanostructures.…”

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confidence: 99%

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Ferromagnetism in Gd doped ZnO nanowires: A first principles study

Aravindh

Schwingenschloegl

Roqan

2014

Journal of Applied Physics

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Size effects on formation energies and electronic structures of oxygen and zinc vacancies in ZnO nanowires: A first-principles study J. Appl. Phys. 109, 044306 (2011) In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48 O 48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of 2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high T C in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV

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Optical and magnetic properties of Nd‐doped ZnO nanoparticles

Zheng

Song

Zhao

et al. 2012

Cryst. Res. Technol.

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Nd‐doped ZnO nanoparticles with different concentration were synthesized by sol‐gel method. The structures, magnetic and optical properties of as‐synthesized nanorods were investigated. X‐ray diffraction (XRD) and x‐ray photoelectron spectroscopy (XPS) results demonstrated that Nd ions were incorporated into ZnO lattice; but Zn1‐xNdxO nanoparticles with Nd concentration of x = 0.05 showed Nd2O3 phase, so the saturation concentration of Nd in Zn1‐xNdxO is less than 5 at%. Vibrating sample magnetometer (VSM) measurements indicated that Nd doped ZnO possessed dilute ferromagnetis behaviour at room temperature. Photoluminescence spectroscopy (PL) showed that Nd ions doping induced a red slight shift and decrease in UV emission with increase of Nd concentration.

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Electrical and magnetic properties of RE-doped ZnO thin films (RE = Gd, Nd)

Cited by 76 publications

References 6 publications

Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

Electrostatic tuning of Kondo effect in a rare-earth-doped wide-band-gap oxide

Ferromagnetism in Gd doped ZnO nanowires: A first principles study

Optical and magnetic properties of Nd‐doped ZnO nanoparticles

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