Magnetic Interactions in Granular Paramagnetic–Ferromagnetic GaAs: Mn/MnAs Hybrids

Heimbrodt, W.; Klar, Peter J.; Ye, S.; Lampalzer, M.; Michel, C.; Baranovskiǐ, S. D.; Thomas, P.; Stolz, W.

doi:10.1007/s10948-005-0001-6

Cited by 24 publications

(33 citation statements)

References 17 publications

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“…A similar behavior is commonly observed for GaMnAs/MnAs hybrid structures, where MnAs nanoclusters of different shapes are randomly distributed in the GaMnAs matrix. 5,11,12 The mechanisms of the charge transport in both hybrid systems is comparable as it occurs via holes in the p-type paramagnetic semiconductor, GaInMnAs and GaMnAs, respectively.…”

Section: -2mentioning

confidence: 97%

“…Thus, the trapped carriers may be released leading to the negative MR effect. 5 The positive MR effect can be explained by assuming different minority and majority spins of the carriers in the matrix and in the clusters. Without an external field, the occupation numbers for both spin orientations in the matrix are equal, however, one spin orientation of the carriers ͑majority carriers͒ can pass preferably through the clusters due to their high spin polarization at the Fermi-energy.…”

Section: -2mentioning

confidence: 99%

“…4,5 Additionally their properties can be tuned in a wide range. This tunability arises from the large number of degrees of freedom, e.g., the mean distance between the clusters, the cluster size, and the cluster shape.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the magnetic properties of GaInAs/MnAs and GaAs/MnAs hybrids with random and ordered arrangements of MnAs nanoclusters

Elm

Michel

Stehr

et al. 2010

Journal of Applied Physics

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Random arrangements of ferromagnetic MnAs nanoclusters were deposited on ͑111͒B-GaInAs surfaces by standard metal-organic vapor-phase epitaxy ͑MOVPE͒. Ordered arrangements of MnAs nanoclusters and cluster chains were obtained by selective-area MOVPE on prepatterned ͑111͒B-GaAs substrates. This new method enables one to control the arrangement of nanoclusters in the growth process offering interesting opportunities to tune the properties of individual MnAs clusters as well as the interaction between the carriers in the surrounding semiconductor matrix and the clusters. The magnetic anisotropy of the MnAs clusters was investigated by magnetic force microscopy and ferromagnetic resonance measurements. The in-plane magnetic anisotropy is mainly determined by the interplay of cluster shape and magnetocrystalline anisotropy while the hard magnetic axis of the clusters is perpendicular to the sample plane independent of cluster shape. The magnetotransport measurements demonstrate that the cluster arrangements strongly influence the transport properties.

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Section: -2mentioning

confidence: 97%

Section: -2mentioning

confidence: 99%

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Comparison of the magnetic properties of GaInAs/MnAs and GaAs/MnAs hybrids with random and ordered arrangements of MnAs nanoclusters

Elm

Michel

Stehr

et al. 2010

Journal of Applied Physics

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“…These usually show a dominant negative MR effect. 4,15,21,22 The strong differences in the transport behavior are caused by different Mn distributions in the matrix, where the transport takes place. In the case of the cluster-chain arrangements, the prepatterning of the sample surface with a SiO 2 mask inhibits a diffusion of Mn into the matrix, which is responsible for its p-type conductivity.…”

Section: Resultsmentioning

confidence: 99%

“…[3][4][5] Moreover, the large number of degrees of freedom in such a composite material results in a huge tunability of its properties compared with a single-phase material, making the hybrids a promising material system for new magnetoelectronic devices. For example, the cluster size strongly contributes to the hybrids' properties.…”

Section: Introductionmentioning

confidence: 99%

Influence of ordered arrangements of cluster chains on the hopping transport in GaAs:Mn/MnAs hybrids at low temperatures

et al. 2011

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Two different arrangements of cluster chains consisting of elongated MnAs nanoclusters were deposited on (111)B-GaAs substrates by selective-area metal-organic vapor-phase epitaxy. This method allows one a controlled positioning of the nanoclusters on the substrate, offering the possibility to investigate the influence of the nanocluster arrangement on the transport properties of granular hybrid structures. Magnetotransport measurements at low temperatures were performed for both cluster-chain arrangements prepared. In contrast to GaAs:Mn/MnAs hybrids with a random cluster distribution, which usually show a negative magnetoresistance at low temperatures, large positive magnetoresistance effects are observed for cluster-chain arrangements at 15 K. Furthermore, the arrangements exhibit a rectifying behavior of the current-voltage characteristics in the presence of an external magnetic field. The magnitude of both effects correlates with the arrangement of the chains on the substrate and can be explained qualitatively by assuming hopping conduction as the dominant transport mechanism.

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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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Magnetic Interactions in Granular Paramagnetic–Ferromagnetic GaAs: Mn/MnAs Hybrids

Cited by 24 publications

References 17 publications

Comparison of the magnetic properties of GaInAs/MnAs and GaAs/MnAs hybrids with random and ordered arrangements of MnAs nanoclusters

Comparison of the magnetic properties of GaInAs/MnAs and GaAs/MnAs hybrids with random and ordered arrangements of MnAs nanoclusters

Influence of ordered arrangements of cluster chains on the hopping transport in GaAs:Mn/MnAs hybrids at low temperatures

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

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