Zinc-blende-type MnAs nanoclusters embedded in GaAs

Yokoyama, Masafumi; Yamaguchi, Hiroshi; Ogawa, Takaki; Tanaka, Mitsugu

doi:10.1063/1.1852214

Cited by 106 publications

(105 citation statements)

References 10 publications

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Section: Nonuniform Ferromagnetic Dms -Chemicalmentioning

confidence: 99%

“…Nevertheless, its presence was found by transmission electron microscopy (TEM) [26,27] in (Ga,Mn)As, as shown in Fig. 1, where coherent zinc-blende Mn-rich (Mn,Ga)As metallic nanocrystals led to the apparent Curie temperature up to 360 K [27]. Furthermore, coherent hexagonal and diamond-type Mn-rich nanocrystals were detected by spatially resolved X-ray diffraction in (Ga,Mn)N [28] and by TEM in (Ge,Mn) [29,30], respectively.…”

Section: Nonuniform Ferromagnetic Dms -Chemicalmentioning

confidence: 99%

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High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

Dietl

2007

Acta Phys. Pol. A

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In this paper the present understanding of the origin of ferromagnetic response that has been detected in a number of diluted magnetic semiconductors and diluted magnetic oxides at room temperature is outlined. It is argued that in these systems, owing to a typically small solubility of magnetic ions, crystallographic or chemical phase separation into regions with a large and a small concentration of magnetic component takes place. The ferromagnetic signatures then come from the regions with a large concentration of magnetic ions, which show non-zero spontaneous magnetization up to the blocking temperature, whose magnitude is proportional to the nanocrystal volume and magnetic anisotropy. Novel methods enabling a control of nano-assembling of magnetic nanocrystals in non-conducting matrices as well as possible functionalities of these spatially modulated magnetic systems are described. We also discuss phase separations into paramagnetic and ferromagnetic regions, which are driven by the Anderson-Mott localization and/or competing ferromagnetic and antiferromagnetic interactions. Finally, the question whether the high temperature ferromagnetism is possible in materials without magnetic ions is addressed.

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Section: Nonuniform Ferromagnetic Dms -Chemicalmentioning

confidence: 99%

Section: Nonuniform Ferromagnetic Dms -Chemicalmentioning

confidence: 99%

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

Dietl

2007

Acta Phys. Pol. A

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“…Large scale applicability of ferromagnetic semiconductors is limited by the Curie temperature, which for GaMnAs layer is below 200 K. In this material the ferromagnetic precipitates are easily produced, yielding multi-phase granular materials as an effect of high temperature annealing at 400 -700 °C of the GaMnAs layers [2,3] or the Mn-implanted GaAs crystals [4]. It is now commonly accepted that annealing the low temperature grown epilayer at the temperature around 500 °C produces small cubic clusters of zinc-blende type (ZB) but annealing starting from 600 °C and higher, results in formation of larger NiAs-type MnAs nanoclusters [2,3]. Therefore, in many studies, without checking this experimentally, it is a priori assumed that appropriate inclusions have been formed [5].…”

Section: Introductionmentioning

confidence: 99%

The source of room temperature ferromagnetism in granular GaMnAs layers with zinc blende clusters

Ławniczak-Jabłońska

Libera

Wolska

et al. 2010

Physica Rapid Research Ltrs

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Granular GaAs:(Mn,Ga)As films were prepared by annealing the Ga0.985Mn0.015As/GaAs layers at 500 °C or 600 °C. It is commonly accepted that this processing should result in the formation of cubic or hexagonal MnAs clusters, respectively. We demonstrate that such a priori assumption is not justified. If in the as grown sample there are not many defects with the interstitial Mn atoms, only small cubic clusters can be formed even after annealing at 600 °C. Moreover, in a sample containing solely cubic GaMnAs clusters, the Mn ions are ferromagnetically coupled at room temperature. This fact was explained by the existence of GaMnAs solid solution in the clusters, with content of Mn close to 20% (higher than ever found in the layers) as was confirmed by experiment and theory. Extended X‐ray absorption spectroscopy studies excluded the possibility of formation of the hypothetic zinc blende MnAs clusters. Not more than one Mn atom was detected in the second shell around central Mn atom. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…The highest T C reported so far for this compound is about 190K (Chen et al, 2009) which is too low for application purposes. These obstacles focused the attention on the ferromagnetic MnAs precipitates which can be quite easily produced by high temperature annealing of the Ga 1-x Mn x As layers (Yokoyama et al, 2005;Kwiatkowski et al, 2007;Demchenko et al, 2007) or by Mn implantation (Couto et al, 2005). Such heterostructures created by introducing ferromagnetic inclusions in a semiconductor matrix became promising.…”

Section: Introductionmentioning

confidence: 99%

MnSb inclusions in the GaSb matrix studied by X-ray absorption spectroscopy

Wolska

Klepka

Ławniczak-Jabłońska

et al. 2011

Radiation Physics and Chemistry

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The MBE processes were performed in order to form the MnSb inclusions. Two kinds of substrates (GaSb and GaAs) as well as growth temperatures (450°C and 520°C) were examined. The SEM imaging was performed to determine the shape and size of formed inclusions. In all samples the inclusions of few hundred nm were formed. Their shapes depended strongly on the type of substrate while the size slightly increases with the growth temperature. The X-ray absorption techniques were used to monitor the local structure around Mn atoms and confirmed that the neighborhood of Mn atoms in the layers was close to that of the MnSb reference powder. We succeed in the formation of the GaSb layers with Mn assembled only into MnSb inclusions on both types of substrates: GaAs(111)A and GaSb(100). However, in case of the GaAs(111)A substrates, the atomic order around Mn atoms in MnSb inclusions is less perfect than in case of the GaSb(100) substrates.

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Zinc-blende-type MnAs nanoclusters embedded in GaAs

Cited by 106 publications

References 10 publications

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

The source of room temperature ferromagnetism in granular GaMnAs layers with zinc blende clusters

MnSb inclusions in the GaSb matrix studied by X-ray absorption spectroscopy

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