Anisotropic strain fields in granular GaAs:MnAs epitaxial layers: Towards self-assembly of magnetic nanoparticles embedded in GaAs

Moreno, María N.; Jenichen, B.; Däweritz, L.

doi:10.1116/1.1943445

Cited by 7 publications

(21 citation statements)

References 38 publications

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“…43 It has been theoretically shown that reduction of misfit stresses tends to cause the preferred crystal lattice orientations of nanoparticles in a composite film. We propose that these changes arise as a result of the nearly tenfold difference between the thermal expansion coefficients of MnP and GaP, thereby considerably modifying the lattice misfit at the matrix/cluster interfaces for different growth temperatures.…”

Section: A Growth Modelmentioning

confidence: 99%

MnP nanoclusters embedded in GaP epitaxial films grown by organometallic vapor-phase epitaxy: A reciprocal space mapping and transmission electron microscopy study

Lambert-Milot¹,

Gaudet²,

Lacroix³

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Full three dimensional x-ray diffraction reciprocal space maps combined with transmission electron microscopy measurements provide a systematic determination of the texture of GaP epilayers containing embedded MnP nanoclusters grown on GaP(001) by organometallic vapor phase epitaxy. This approach reveals that the texture of the MnP clusters depends on the growth surface morphology and bonding configuration and on the lattice mismatch at the cluster/matrix interfaces during growth. It demonstrates that the orthorhombic MnP nanoclusters are oriented along specific GaP crystallographic directions, forming six well defined families, whose population is influenced by the growth temperature and the film thickness. The clusters principally grow on GaP(001) and GaP{111} facets with a small fraction of clusters nucleating on higher-index GaP{hhl} facets. Most epitaxial alignments share a similar component: the MnP(001) plane (c-axis plane) is parallel to the GaP{110} plane family. Axiotaxial ordering between the MnP clusters and the GaP matrix is also observed. Furthermore, with this systematic approach, all phases present in these heterogeneous films can be identified. In particular, traces of hexagonal Mn2P precipitates have been observed while their formation can be avoided by lowering the growth temperature. Comparing the structural results presented here with magnetic measurement carried out on similar samples confirms that the effective magnetic properties of the heterogeneous layer can be tuned by controlling the texture of the ferromagnetic nanoclusters.

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Section: A Growth Modelmentioning

confidence: 99%

MnP nanoclusters embedded in GaP epitaxial films grown by organometallic vapor-phase epitaxy: A reciprocal space mapping and transmission electron microscopy study

Lambert-Milot¹,

Gaudet²,

Lacroix³

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

View full text Add to dashboard Cite

show abstract

“…[23][24][25][26] After HT annealing, the difference between the lattice constant of the layer originally constituting the (Ga,Mn)As ternary alloy and the lattice constant of the GaAs substrate is due only to strain in the GaAs host lattice caused by the presence of Mn-rich clusters. [27][28][29] The clusters themselves do not contribute to the diffraction peaks shown in Fig. 1.…”

Section: Structural Propertiesmentioning

confidence: 99%

“…It is known from previous reports, that Mn-rich nanocrystals can exert a compressive strain on a surrounding GaAs matrix. [27][28][29] Since the in-plane lattice parameter of the layer is fixed to shows the strain calculated from the lattice constants obtained from angular positions of diffraction peaks shown in Fig. 1.…”

Section: Structural Propertiesmentioning

confidence: 99%

“…In this paper, we study the properties of (Mn,Ga)As:GaAs phase-separated material produced by moderate-to-high temperature annealing of LT MBE-grown (Ga,Mn)As ternary alloys. Although many literature reports on this system have been published, both prior to 12 and after [13][14][15] the first successful growth of (Ga,Mn)As ferromagnetic semiconductor, 18 there are still unexplained issues concerning both the properties of the (Mn,Ga)As:GaAs granular system and the detailed mechanisms of the formation of (Mn,Ga)As nanocrystals. Even basic characteristics of the (Mn,Ga)As inclusions, such as their compositions, are not yet 4 sufficiently well understood.…”

Section: Introductionmentioning

confidence: 99%

“…Zinc-blende (Mn,Ga)As nanocrystals with larger sizes were not observed either in our TEM images, or in TEM results published by other groups. 9,27,28,30 The magnetic properties of granular system with two kinds of nanoparticles are not trivial to understand. In ferrofluids composed of single-domain magnetic nanoparticles separated by surfactants, superparamagnetism is usually observed in systems in which the nanoparticles do 17 not interact magnetically.…”

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confidence: 99%

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Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content

et al. 2011

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corresponding author e-mail: janusz.sadowski@maxlab.lu.se 2 X-ray diffraction, transmission electron microscopy, and magnetization measurements are employed to study the structural and magnetic properties of Mn-rich (Mn,Ga)As nanocrystals embedded in GaAs. These nanocomposites are obtained by moderate (400 o C) and high temperature (560 and 630 o C) annealing of (Ga,Mn)As layers with Mn concentrations between 0.1 and 2%, grown by molecular beam epitaxy at 270 o C. Decomposition of (Ga,Mn)As is already observed at the lowest annealing temperature of 400 o C for layers with initial Mn content of 1% and 2%. Both cubic and hexagonal (Mn,Ga)As nanocrystals, with similar diameters of 7 -10 nm are observed to coexist in layers with an initial Mn content of 0.5% after higher temperature annealing. Measurements of magnetization relaxation in the time span 0.1 -10 000 s provide evidence for superparamagnetic properties of the (Mn,Ga)As nanocrystals, as well as for the absence of spin-glass dynamics. These findings point to weak coupling between nanocrystals even in layers with the highest nanocrystal density.

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Transport Properties of Hybrids with Ferromagnetic MnAs Nanoclusters and Their Potential for New Magnetoelectronic Devices

Elm

Hara

2014

Advanced Materials

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Granular hybrid structures containing ferromagnetic nanoclusters embedded in a semiconducting matrix are an interesting class of materials as their properties can be tuned in a wide range. Hybrids are a promising alternative to dilute magnetic semiconductors in the field of spintronics and magnetoelectronics, because the nanoclusters can show ferromagnetic behavior even at room temperature. In this review, it is focused on the rather well investigated dilute magnetic semiconductor (Ga,Mn)As with MnAs inclusions. Different preparation methods are presented which were developed over the last two decades in order to obtain MnAs nanoclusters in the semiconducting matrix and to tune the structural and magnetic properties of these clusters. Recent results on the influence of the nanoclusters on the hybrids' transport properties as well as first approaches to use hybrids with a random nanocluster distribution in new spintronic devices are discussed. In addition, the perspective of using single MnAs nanoclusters as well as ordered arrangements of a few nanoclusters in new planar magnetoelectronic devices is illustrated.

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Anisotropic strain fields in granular GaAs:MnAs epitaxial layers: Towards self-assembly of magnetic nanoparticles embedded in GaAs

Cited by 7 publications

References 38 publications

MnP nanoclusters embedded in GaP epitaxial films grown by organometallic vapor-phase epitaxy: A reciprocal space mapping and transmission electron microscopy study

MnP nanoclusters embedded in GaP epitaxial films grown by organometallic vapor-phase epitaxy: A reciprocal space mapping and transmission electron microscopy study

Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs fabricated by annealing of (Ga,Mn)As layers with low Mn content

Transport Properties of Hybrids with Ferromagnetic MnAs Nanoclusters and Their Potential for New Magnetoelectronic Devices

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