Double Resonance Mechanism of Ferromagnetism and Magnetotransport in (Ga-Mn)As

Inoue, Jun–ichiro; Nonoyama, Shinji; Itoh, H.

doi:10.1103/physrevlett.85.4610

Cited by 92 publications

(68 citation statements)

References 24 publications

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“…Indeed, most band structure calculations predict a substantial hybridization of the GaAs bands with Mn d levels in this doping regime. [6][7][8][9][10][11][12][13] Experimental verification of this proposal is found in the results of core-level photoemission experiments which indicate a strong As 4p Mn 3d hybridization. 14 Direct measurements of the electronic states in Ga 1Ϫx Mn x As from angle resolved photoemission spectroscopy ͑ARPES͒ show Mninduced states both 3-4 eV below the top of the valence band, and also very near the Fermi energy (E F ).…”

Section: Introductionmentioning

confidence: 59%

“…According to one school of thought, the doped carriers are assumed to reside in an impurity band ͑IB͒. 6,9,20,21,28,48,49 This picture stems from the fact that Mn is known to form a shallow acceptor level in GaAs when the doping is weak (10 17 cm Ϫ3 ). 4,5 The impurity band scenario assumes that as doping progresses from this very dilute limit, to the heavily doped regime, the shallow Mn acceptor level broadens and forms an impurity band ͑panel B in Fig.…”

Section: B Electronic Structure Of Ferromagnetic Ga 1àx Mn X Asmentioning

confidence: 99%

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Electronic structure and carrier dynamics of the ferromagnetic semiconductorGa1−xMnxAs<

et al. 2003

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Infrared spectroscopy is used to study the doping and temperature dependence of the intragap absorption in the ferromagnetic semiconductor Ga 1Ϫx Mn x As, from a paramagnetic, xϭ0.017 sample to a heavily doped, xϭ0.079 sample. Transmission and reflectance measurements coupled with a Kramers-Kronig analysis allow us to determine the optical constants of the thin films. All ferromagnetic samples show a broad absorption resonance near 200 meV, within the GaAs band gap. We present a critical analysis of possible origins of this feature, including a Mn-induced impurity band and intervalence band transitions. The overall magnitude of the real part of the frequency dependent conductivity grows with increasing Mn doping, and reaches a maximum in the xϭ0.052 sample where T C saturates at the highest value (ϳ70 K) for the series. We observe spectroscopic signatures of compensation and track its impact on the electronic and magnetic state across the Mn phase diagram. The temperature dependence of the far infrared spectrum reveals a significant decrease in the effective mass of itinerant carriers in the ferromagnetic state. A simple scaling relation between changes in the mass and the sample magnetization suggest that the itinerant carriers play a key role in producing the ferromagnetism in this system.

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Section: Introductionmentioning

confidence: 59%

Section: B Electronic Structure Of Ferromagnetic Ga 1àx Mn X Asmentioning

confidence: 99%

Electronic structure and carrier dynamics of the ferromagnetic semiconductorGa1−xMnxAs<

et al. 2003

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“…Within the context of DMS, the Anderson Hamiltonian for a semiconductor host was also considered by Krstajić et al [25], and it was shown that an FM interaction is generated between the impurities due to kinematic exchange. The role of IBS in producing the FM interaction in DMS was also discussed within the "double resonance mechanism" using HF [26].…”

Section: Introductionmentioning

confidence: 99%

Crystal structure effect on the ferromagnetic correlations in ZnO with magnetic impurities

Bulut

Maekawa

2008

Journal of Applied Physics

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We study the ferromagnetism in the compound (Zn,Mn)O within the Haldane-Anderson impurity model by using the quantum Monte Carlo technique and the tight-binding approximation for determining the host band-structure and the impurity-host hybridization. This computational approach allows us to determine how the host crystal structure influences the impurity bound state, which plays an important role in the development of the ferromagnetic (FM) correlations between the impurities. We find that the FM correlations are strongly influenced by the crystal structure. In particular, in p-type (Zn,Mn)O, we observe the development of FM correlations with an extended range at low temperatures for wurtzite and zincblende crystal structures. However, for the rocksalt structure no FM correlations are observed between the impurities. In addition, in n-type ZnO with magnetic impurities, the impurity bound state and FM correlations are not found.

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“…Theoretical studies using state-of-the-art computational methods have been made in order to discover the mechanisms behind ferromagnetism in semiconductors [12,13,14,15,16,17,18,19,20]. On the other hand, in a phenomenological mean-field model the magnetic interactions can be described with an exchange constant [16,21].…”

mentioning

confidence: 99%

Intrinsic hole localization mechanism in magnetic semiconductors

Raebiger¹,

Ayuela²,

Nieminen³

2004

J. Phys.: Condens. Matter

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Abstract. -The interplay between clustering and exchange coupling in magnetic semiconductors for the prototype (Ga1−x, Mnx)As with manganese concentrations x of 1/16 and 1/32 in the interesting experimental range is investigated. For x ∼ 6%, when all possible arrangements of two atoms within a large supercell are considered, the clustering of Mn atoms at nearest-neighbour Ga sites is energetically preferred. As shown by spin density analysis, this minimum energy configuration localizes further one hole and reduces the effective charge carrier concentration. Also the exchange coupling constant increases to a value corresponding to lower Mn concentrations with decreasing inter Mn distance.Including spin information into semiconductor electronics has enormous potential for new applications (see Ref.[1] for a review on magnetoelectronics). An interesting situation arises when the carriers responsible for metallic behaviour are of the same spin, in the so called half-metals [2]. Within this class of materials, the magnetic semiconductors are particularly challenging, not only because they can replace magnetic elements in storage media, but because they can be used as spin injectors into normal semiconductors [3,4] for completely novel applications. In the field of magnetic semiconductors a new chapter has been opened by the III-V diluted magnetic semiconductors (DMS), especially with (Ga, Mn)As.Experimentally (Ga, Mn)As can be manufactured using low-temperature molecular beam epitaxy (LT-MBE) [5,6,7,8] and its magnetic properties have been measured with numerous techniques [5,6,7,8,9,10,11]. (Ga,Mn)As is ferromagnetic (see e.g. Refs. [6, 7, 8]), with a Curie temperature as large as 110 K in the Mn concentration range between 5% and 10%. In addition, the temporal evolution of the magnetization during annealing shows that first ferromagnetism is enhanced and then reduced, [11], suggestive of clustering processes.In this Letter, we first survey the current state of theoretical research in the field. To overcome all the possible sources of errors a new benchmark is needed. We then present calculations for magnetic semiconductors, studying (Ga 1−x , Mn x )As in different magnetic configurations. In particular, we assess the role of Mn clustering in the lattice (see Fig.1 describing the considered cases). Finally, the clustering results drive us to reexamine the findings of previous calculations that address the role of the exchange coupling parameter within mean-field theories.The ferromagnetism (FM) in (Ga,Mn)As is mediated by holes that are antiferromagnetically (AFM) coupled to the Mn. Theoretical studies using state-of-the-art computational c EDP Sciences

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Double Resonance Mechanism of Ferromagnetism and Magnetotransport in (Ga-Mn)As

Cited by 92 publications

References 24 publications

Electronic structure and carrier dynamics of the ferromagnetic semiconductorGa1−xMnxAs<

Electronic structure and carrier dynamics of the ferromagnetic semiconductorGa1−xMnxAs<

Crystal structure effect on the ferromagnetic correlations in ZnO with magnetic impurities

Intrinsic hole localization mechanism in magnetic semiconductors

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