First-principles calculations of electronic structures of diluted magnetic semiconductors (Ga,Mn)As

Ogawa, Takaki; Shirai, Masamitsu; Suzuki, N.; Kitagawa, Isao

doi:10.1016/s0304-8853(98)00794-x

Cited by 107 publications

(47 citation statements)

References 6 publications

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“…Hence, if the spin polarizations P G and P M are known, we can estimate the efficiency of spin polarized injection through the tunnel barrier as a ratio of the observed TMR to the ideal TMR predicted by the above equation. While direct measurements of P G and P M are not available at present, band structure calculations predict 100 % spin-polarization in Ga 1−x Mn x As with x ≥ 0.125 [21] and for (hypothetical) zinc-blende MnAs. [22] However, when MnAs is in the NiAs structure, it is not half-metallic and the theoretical value of the spin polarization is about 0.3.…”

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confidence: 99%

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Spin-polarized tunneling in hybrid metal-semiconductor magnetic tunnel junctions

Chun

Potashnik

et al. 2002

Phys. Rev. B

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We demonstrate efficient spin-polarized tunneling between a ferromagnetic metal and a ferromagnetic semiconductor with highly mismatched conductivities. This is indicated by a large tunneling magnetoresistance (up to 30%) at low temperatures in epitaxial magnetic tunnel junctions composed of a ferromagnetic metal (MnAs) and a ferromagnetic semiconductor (Ga 1−x Mn x As) separated by a nonmagnetic semiconductor (AlAs). Analysis of the current-voltage characteristics yields detailed information about the asymmetric tunnel barrier. The low temperature conductancevoltage characteristics show a zero bias anomaly and a √ V dependence of the conductance, indicating a correlation gap in the density of states of Ga 1−x Mn x As. These experiments suggest that MnAs/AlAs heterostructures offer well characterized tunnel junctions for high efficiency spin injection into GaAs.

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confidence: 99%

“…[21] We can rule out spurious effects that might artificially enhance TMR in our measurements. First, the magnetoresistances of individual MnAs and Ga 1−x Mn x As layers are smaller than 0.5 % for the field range shown in Figure 1(b).…”

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confidence: 99%

Spin-polarized tunneling in hybrid metal-semiconductor magnetic tunnel junctions

Chun

Potashnik

et al. 2002

Phys. Rev. B

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“…(Ga,Mn)As/n-GaAs spin Esaki diodes on the other hand showed high spin injection efficiency exceeding 50% at low bias 2 owing to the high spin polarization of (Ga,Mn)As. 16,17 While a full theoretical understanding of DNP in allelectrical spin injection devices with lateral structures has not fully been established yet, the nuclear magnetic field is proportional to the spin polarization of electrons in the chan-…”

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Dynamic nuclear spin polarization in an all-semiconductor spin injection device with (Ga,Mn)As/n-GaAs spin Esaki diode

Shiogai

Ciorga

Utz

et al. 2012

Applied Physics Letters

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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].…”

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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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First-principles calculations of electronic structures of diluted magnetic semiconductors (Ga,Mn)As

Cited by 107 publications

References 6 publications

Spin-polarized tunneling in hybrid metal-semiconductor magnetic tunnel junctions

Spin-polarized tunneling in hybrid metal-semiconductor magnetic tunnel junctions

Dynamic nuclear spin polarization in an all-semiconductor spin injection device with (Ga,Mn)As/n-GaAs spin Esaki diode

Intrinsic hole localization mechanism in magnetic semiconductors

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