Origin of low-temperature magnetic ordering in Ga<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math>Mn<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mi>x</mml:mi></mml:msub></mml:math>N

Sawicki, M.; Devillers, Thibaut; Galeski, Stanislaw; Simserides, Constantinos; Dobkowska, S.; Faina, B.; Grois, Andreas; Navarro-Quezada, A.; Trohidou, K. N.; Majewski, J. A.; Dietl, T.; Bonanni, A.

doi:10.1103/physrevb.85.205204

Cited by 55 publications

(71 citation statements)

References 44 publications

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“…The coupled spin-and charge-doping also creates difficulties in establishing the connection between host properties and figures of merit [13]. For example, a prediction of T C > 300 K in GaN:Mn [14] has stimulated a lot of efforts that turned out to be fruitless [15,16]. Finally, both substitutional and interstitial Mn are thermodynamically stable and form during synthesis, which additionally complicates theoretical treatment.…”

Section: Introduction-mentioning

confidence: 99%

Theory of Mn-doped II-II-V semiconductors

2014

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A recently discovered magnetic semiconductor Ba1−xKx(Zn1−yMny)2As2, with its decoupled spin and charge doping, provides a unique opportunity to elucidate the microscopic origin of the magnetic interaction and ordering in dilute magnetic semiconductors (DMS). We show that (i) the conventional density functional theory (DFT) accurately describes this material, and (ii) the magnetic interaction emerges from the competition of the short-range superexchange and a longer-range interaction mediated by the itinerant As holes, coupled to Mn via the Schrieffer-Wolff p−d interaction representing an effective Hund's rule coupling, J eff H . The key difference between the classical double exchange and the actual interaction in DMS is that an effective J eff H , as opposed to the standard Hund's coupling JH , depends on the Mn d−band position with respect to the Fermi level, and thus allows tuning of the magnetic interactions. The physical picture revealed for this transparent system may also be applicable to more complicated DMS systems.Introduction-The carrier-mediated magnetism in DMS [1-5] offers a versatile control of the exchange interaction by tuning the Curie temperature T C through changes in the carrier density [5][6][7][8]. However, despite four decades of intensive work, challenges remain and materials complexity often hinders theoretical understanding. The origin of magnetic ordering [1-3, 5] and paths to higher T C remain strongly debated [3,9,10].

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Section: Introduction-mentioning

confidence: 99%

Theory of Mn-doped II-II-V semiconductors

2014

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“…While the search for a technology-viable magnetic semiconductor at room temperature is still the subject of active research a great deal of knowledge on the underlying physical processes can be gained from the investigation of various systems at their relevant temperatures [1]. Our material of choice is (Ga,Mn)N -an emerging ferromagnetic semiconductor whose long range ferromagnetic ordering has been confirmed at the low end of cryogenic temperatures [2,3]. The importance of GaN-based compounds and heterostructures stems from the growing significance of wide band-gap materials in conventional electronics, particularly in opto-and high power electronics.…”

Section: Introductionmentioning

confidence: 99%

Two-Probe Measurements of Electron Transport in GaN:Si/(Ga,Mn)N/GaN:Si Spin Filter Structures

et al. 2016

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“…Third, and most recently, the ferromagnetic coupling in insulating systems was also interpreted in terms of super exchange. 33,34 In this paper, as an illustration of our formalism, we systematically study the metal-insulator transition due to localization in the ferromagnetic phase of (Ga,Mn)N. We find that (Ga,Mn)N is always insulating within the compositional limit consistent with transport measurements. 49 Our results indicate that both the second and the third models are important to explain the magnetism in this material.…”

Section: Introductionmentioning

confidence: 59%

“…33 and 34. For x > 0.03, a nonmagnetic dopant such as Zn, or e.g., the application of a gate bias, could move the chemical potential down, leading to a metallic phase with ferromagnetism induced by double exchange as well as superexchange 33,34 possibly enhancing the Curie temperature significantly.…”

Section: Resultsmentioning

confidence: 99%

“…This implies that ferromagnetism in Ga 1−x Mn x N for x ≤ 0.03 cannot be mediated by double exchange, which would require itinerant carriers in the impurity band. For larger concentrations, chemical doping or the application of a gate bias could move the chemical potential down, leading to a metallic phase with ferromagnetism induced by double exchange as well as superexchange 33,34 possibly enhancing the Curie temperature significantly.…”

Section: Discussionmentioning

confidence: 99%

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Generalized multiband typical medium dynamical cluster approximation: Application to (Ga,Mn)N

et al. 2016

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We generalize the multiband typical medium dynamical cluster approximation and the formalism introduced by Blackman, Esterling and Berk so that it can deal with localization in multiband disordered systems with both diagonal and off-diagonal disorder with complicated potentials. We also introduce a new ansatz for the momentum resolved typical density of states that greatly improves the numerical stability of the method, while preserving the independence of scattering events at different frequencies. Starting from the first-principles effective Hamiltonian, we apply this method to the diluted magnetic semiconductor Ga1−xMnxN, and find the impurity band is completely localized for Mn concentrations x < 0.03, while for 0.03 < x < 0.10 the impurity band has delocalized states but the chemical potential resides at or above the mobility edge. So, the system is always insulating within the experimental compositional limit (x ≈ 0.10) due to Anderson localization. However, for 0.03 < x < 0.10 hole doping could make the system metallic allowing double exchange mediated, or enhanced, ferromagnetism. The developed method is expected to have a large impact on first-principles studies of Anderson localization.

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Origin of low-temperature magnetic ordering in Ga1−xMnxN

Cited by 55 publications

References 44 publications

Theory of Mn-doped II-II-V semiconductors

Theory of Mn-doped II-II-V semiconductors

Two-Probe Measurements of Electron Transport in GaN:Si/(Ga,Mn)N/GaN:Si Spin Filter Structures

Generalized multiband typical medium dynamical cluster approximation: Application to (Ga,Mn)N

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