Quantum size effect transition in percolating nanocomposite films

Raquet, Bertrand; Goiran, M.; Nègre, Nicolas; Leotin, J.; Аронзон, Б. А.; Rylkov, V. V.; Meĭlikhov, E. Z.

doi:10.1103/physrevb.62.17144

Cited by 27 publications

(7 citation statements)

References 45 publications

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“…Venkatesan, Ogale, and co‐workers have also carried out considerable work on DMSO systems 53–63. They have elucidated the role of growth‐condition‐dependent dopant clustering and the occurrence of AHE even in the dopant‐clustered case thereby questioning the validity of AHE as an unambiguous signature of intrinsic DMS (with R. L. Greene).…”

Section: 1 Magnetism In Tio2 With Dilute Doping Of Transition Elemmentioning

confidence: 99%

Dilute Doping, Defects, and Ferromagnetism in Metal Oxide Systems

2010

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Over the past decade intensive research efforts have been carried out by researchers around the globe on exploring the effects of dilute doping of magnetic impurities on the physical properties of functional non-magnetic metal oxides such as TiO(2) and ZnO. This effort is aimed at inducing spin functionality (magnetism, spin polarization) and thereby novel magneto-transport and magneto-optic effects in such oxides. After an early excitement and in spite of some very promising results reported in the literature, this field of diluted magnetic semiconducting oxides (DMSO) has continued to be dogged by concerns regarding uniformity of dopant incorporation, the possibilities of secondary ferromagnetic phases, and contamination issues. The rather sensitive dependence of magnetism of the DMSO systems on growth methods and conditions has led to interesting questions regarding the specific role played by defects in the attendant phenomena. Indeed, it has also led to the rapid re-emergence of the field of defect ferromagnetism. Many theoretical studies have contributed to the analysis of diverse experimental observations in this field and in some cases to the predictions of new systems and scenarios. In this review an attempt is made to capture the scope and spirit of this effort highlighting the successes, concerns, and questions.

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Section: 1 Magnetism In Tio2 With Dilute Doping Of Transition Elemmentioning

confidence: 99%

Dilute Doping, Defects, and Ferromagnetism in Metal Oxide Systems

2010

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“…Fitting parameters obtained from the 50 K MR data are a AHE is often conceived as a proof of intrinsic ferromagnetism although it could also originate from metal clusters. 57 To form metal clusters, the magnetic impurity concentration must be high enough to either reach the bulk percolation threshold or lead to the formation of large clusters with a size of ∼10 nm near the interface 57,58 Apparently, those scenarios are highly unlikely in our undoped samples since they were synthesized by using high purity (99.9999%) precursor materials with negligible metal contamination. The anomalous part of ρ xy should be proportional to the magnetization in the regime of low magnetic field, whereas the ordinary Hall effect dominates in the high field regime.…”

Section: Electrical and Magnetotransport Studiesmentioning

confidence: 99%

Defect-induced magnetism in undoped wide band gap oxides: Zinc vacancies in ZnO as an example

Xing¹,

Lu²,

Tian³

et al. 2011

AIP Advances

185

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To shed light on the mechanism responsible for the weak ferromagnetism in undoped wide band gap oxides, we carry out a comparative study on ZnO thin films prepared using both sol-gel and molecular beam epitaxy (MBE) methods. Compared with the MBE samples, the sol-gel derived samples show much stronger room temperature ferromagnetism with a magnetic signal persisting up to ∼740 K, and this ferromagnetic order coexists with a high density of defects in the form of zinc vacancies. The donor-acceptor pairs associated with the zinc vacancies also cause a characteristic orange-red photoluminescence in the sol-gel films. Furthermore, the strong correlation between the ferromagnetism and the zinc vacancies is confirmed by our first-principles density functional theory calculations, and electronic band alteration as a result of defect engineering is proposed to play the critical role in stabilizing the long-range ferromagnetism

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“…[23] and references therein), there has been no previous experimental measurement of the shift of the percolation threshold with changing system size, or of the critical exponent for the correlation length, n. Our choice of a rectangular system is critical in allowing us to address this issue. The present work can be regarded as a direct experimental confirmation of the finite-size effects predicted by percolation theory.…”

mentioning

confidence: 99%

Finite-Size Effects in the Conductivity of Cluster Assembled Nanostructures

et al. 2002

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Atomic clusters have been deposited between lithographically defined contacts with nanometer scale separations. The design of the contacts is based on an appropriate application of percolation theory to conduction in cluster deposited devices and allows finite-size effects to be clearly observed. It is demonstrated, both by experiment and by simulation, that for small contact separations the percolation threshold is shifted to extremely low surface coverages. The selected rectangular contact geometry ensures that wirelike structures are formed close to the percolation threshold.

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Quantum size effect transition in percolating nanocomposite films

Cited by 27 publications

References 45 publications

Dilute Doping, Defects, and Ferromagnetism in Metal Oxide Systems

Dilute Doping, Defects, and Ferromagnetism in Metal Oxide Systems

Defect-induced magnetism in undoped wide band gap oxides: Zinc vacancies in ZnO as an example

Finite-Size Effects in the Conductivity of Cluster Assembled Nanostructures

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