Local structures of III-V diluted magnetic semiconductors<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Mn</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">As</mml:mi></mml:math>studied u

Shioda, R.; Ando, Koji; Hayashi, Toshiaki; Tanaka, Masaaki

doi:10.1103/physrevb.58.1100

Cited by 114 publications

(54 citation statements)

References 16 publications

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“…Hence the annealing increases the concentration of 4p holes. We tentatively assume that Mn which produce spectrum A are those normally replaced the Ga sites 22) and have four nearest neighbor As atoms. Since XAS gives site projected partial density of states, such a Mn is assigned to be Mn-h (As 4p hole) complex.…”

Section: §1 Introductionmentioning

confidence: 99%

Magnetism and metal-insulator transition in III-V based diluted magnetic semiconductors

Katsumoto

Hayashi

Hashimoto

et al. 2001

Materials Science and Engineering: B

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We report experiments on the magnetism and the transport in III-V based diluted magnetic semiconductors (Ga,Mn)As and (In,Mn)As. Heat treatment (annealing) at comparatively low temperatures (slightly above the growth temperature) is unexpectedly found to be effective to improve the ferromagnetism and the metallic conduction. Infrared optical conductivity measurements and soft x-ray absorption spectroscopy reveal that the double exchange model is convenient to describe the ferromagnetism. The transport in the vicinity of metal-insulator critical point was studied in detail by using the low-temperature annealing method. §1 Introduction Diluted magnetic semiconductors (DMS's) synthesized by introduction of magnetic ions into semiconductors are now expanding a new horizon of "spin-electronics". Especially III-V based DMS's (In,Mn)As and (Ga,Mn)As have attracted much attention. They undergo ferromagnetic transition at comparatively high temperatures and have high connectivity to sophisticated III-V artificial superstructures. A remarkable feature of the ferromagnetism is that it is mediated by the doped holes, which fact was demonstrated by illumination-driven ferromagnetic transition 3) and by disappearance of the ferromagnetism by counter doping 4) .However the physical mechanism of the ferromagnetism is still under discussion. In a II-IV DMS, it is claimed that the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction is the origin of the transient ferromagnetism 5) . The transport and the response to external magnetic field in (Ga,Mn)As were analyzed along similar interpretation 6) . This interpretation, however, has an essential difficulty that the estimated amplitude of the exchange constant tends to exceed the Fermi energy. While interpretations to solve this inconsistency were attempted 7) , a calculation of band structure 8) in (In,Mn)As suggested doubleexchange (DE) mechanism is more plausible. Though the result of the band-calculation is also getting experimental supports 9) , decisive evidence has not appeared yet. In a sense, these two pictures describe limiting cases and the reality should exist between them. It would be meaningful, however, to examine which picture is convenient to describe the experiments.These materials also shows exotic properties in transport 10) . Increasing Mn concentration (x) from the dilute limit, they undergo an insulator-to-metal transition (the first MIT). The ferromagnetism appears at a Mn concentration slightly lower than the first MI critical point. Further increase in x causes a metal-to-insulator re-entrant transition (the second MIT).One of the problems in these materials for researches and applications is that the qualities of the grown crystals are too sensitive to the growth conditions because the conditions are very far from equilibrium 11) . In this article, we report that annealing (heat treatment) at comparatively low temperatures partly solve the problem. We apply this method to explore the picture for the ferromagnetism, and the nature of the second MIT. O...

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Section: §1 Introductionmentioning

confidence: 99%

Magnetism and metal-insulator transition in III-V based diluted magnetic semiconductors

Katsumoto

Hayashi

Hashimoto

et al. 2001

Materials Science and Engineering: B

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“…The substitutional nature of Mn ions in the group III sublattices has been demonstrated by extended x-ray absorption fine structure (EXAFS) measurements of low-temperature MBEgrown samples [33,34]. As for the spatial configuration of these defects, most theoretical models for transport in DMSs assume their random distribution.…”

Section: Correlations In Impurity Positionsmentioning

confidence: 99%

Transport and optical conductivity in dilute magnetic semiconductors

Kyrychenko¹,

Ullrich²

2009

J. Phys.: Condens. Matter

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A theory of transport in spin and charge disordered media is developed, with a particular emphasis on dilute magnetic semiconductors. The approach is based on the equation of motion for the current-current response function and considers both spin and charge disorder and electron-electron interaction on an equal footing. The formalism is applied to the specific case of Ga 1−x Mn x As. Within the single parabolic band approximation it is shown that both spin (p-d exchange) and charge (Coulomb) scattering contributions to the resistivity are of the same order of magnitude and should be treated simultaneously. Positional correlations of charged impurities are shown to significantly increase the Coulomb scattering. In the magnetically ordered phase, the suppression of localized spin fluctuations leads to a sizable reduction of spin scattering, which may contribute to the experimentally observed drop in resistivity below the critical temperature. The developed model allows for a comprehensive treatment of electron-electron interaction, screening and correlation effects by means of time-dependent density-functional theory. It is shown that collective modes and a dynamical treatment of electron-electron interaction are essential for an accurate description of the infrared absorption spectrum.

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“…Such model is within the accuracy of EXAFS method providing slightly worse agreement with the experimental data and a quite large error in the parameters of the appropriate scattering path. This scattering path is located at the distance 4.43(16) Å with disorder factor σ 2 = 0.007 (6). The presence of 1 Mn atom in a second shell gives in a 6 nm cluster the concentration of Mn close to 20%.…”

Section: Introductionmentioning

confidence: 99%

“…As a starting model of ZB clusters it was assumed that the distance of the first coordination sphere is equal to 2.55 Å [6]. This value was then refined in the fitting procedure.…”

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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Local structures of III-V diluted magnetic semiconductorsGa1−xMnxAsstudied u

Cited by 114 publications

References 16 publications

Magnetism and metal-insulator transition in III-V based diluted magnetic semiconductors

Magnetism and metal-insulator transition in III-V based diluted magnetic semiconductors

Transport and optical conductivity in dilute magnetic semiconductors

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

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