Berciu and Bhatt Reply:

Berciu, Mona; Bhatt, R. N.

doi:10.1103/physrevlett.90.029702

Cited by 199 publications

(452 citation statements)

References 7 publications

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“…An examination of doping trends allows us to distinguish between two types of compensating defects: As Ga antisites and Mn i interstitials which play a pivotal role in defining both the electronic and magnetic state of the Ga 1Ϫx Mn x As system. [27][28][29] We confirm the existence of the 200 meV resonance in the intragap conductivity of Ga 1Ϫx Mn x As. We show that this feature is specific to the response of ferromagnetic samples.…”

Section: Introductionsupporting

confidence: 62%

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: Introductionsupporting

confidence: 62%

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

et al. 2003

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“…Our magnetization results also agree with the numerical results of Ref. 23,25. Very recently, a direct numerical HartreeFock calculation has convincingly verified the magnetic polaron percolation picture for the localized regime.…”

Section: B Percolation Theorysupporting

confidence: 81%

How to make semiconductors ferromagnetic: a first course on spintronics

Sarma

Hwang

Kaminski

2003

Solid State Communications

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The rapidly developing field of ferromagnetism in diluted magnetic semiconductors, where a semiconductor host is magnetically doped by transition metal impurities to produce a ferromagnetic semiconductor (e.g. Ga1−xMnxAs with x ≈ 1 − 10%), is discussed with the emphasis on elucidating the physical mechanisms underlying the magnetic properties. Recent key developments are summarized with critical discussions of the roles of disorder, localization, band structure, defects, and the choice of materials in producing good magnetic quality and high Curie temperature. The correlation between magnetic and transport properties is argued to be a crucial ingredient in developing a full understanding of the properties of ferromagnetic semiconductors.

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“…In spite of intense experimental and theoretical activity in Ga 1−x Mn x As over the last ten years, the key issue of valence band versus impurity band carriers mediating the DMS ferromagnetism has remained controversial even in the optimally doped, (x ∼ 0.05) nominally metallic, high-T c (T c ∼ 150 − 200K, the ferromagnetic transition temperature or the Curie temperature) Ga 1−x Mn x As material. For example, ab initio first principles band structure calculations 7 typically indicate a strong-coupling narrow impurity band behavior whereas the extensively used phenomenological mean-field description, parameterized by a single effective impurity moment-carrier spin ("pd") exchange interaction 1,3,4,8 , leads to reasonable quantitative agreement with experimental results in the metallic (x ∼ 0.05) Ga 1−x Mn x As requiring a relatively weak exchange coupling (and therefore, a weak perturbation of the GaAs valence band) between the Mn moments and the valence band holes. Similarly, optical absorption spectroscopic data in GaMnAs were first interpreted 9 using an impurity band theoretic description 10 , but later it was shown 11 that the same data could also be explained as arising from the valence band picture.…”

Section: Introductionmentioning

confidence: 99%

Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors

Zhang

Sarma

2005

Phys. Rev. B

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We calculate the Coulomb interaction induced density, temperature and magnetization dependent many-body band-gap renormalization in a typical diluted magnetic semiconductor Ga1−xMnxAs in the optimally-doped metallic regime as a function of carrier density and temperature. We find a large (∼ 0.1eV ) band gap renormalization which is enhanced by the ferromagnetic transition. We also calculate the impurity scattering effect on the gap narrowing. We suggest that the temperature, magnetization, and density dependent band gap renormalization could be used as an experimental probe to determine the valence band or the impurity band nature of carrier ferromagnetism.

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Berciu and Bhatt Reply:

Cited by 199 publications

References 7 publications

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

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

How to make semiconductors ferromagnetic: a first course on spintronics

Temperature and magnetization-dependent band-gap renormalization and optical many-body effects in diluted magnetic semiconductors

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