What is the Valence of Mn in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>Ga</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Mn</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:math>?

Nelson, Ryky; Berlijn, Tom; Moreno, Juana; Jarrell, Mark; Ku, Wei

doi:10.1103/physrevlett.115.197203

Cited by 14 publications

(12 citation statements)

References 68 publications

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“…Are these Mn 0 and Fe + states best described by d 4 or d 5 + h configurations? For Mn 0 , earlier theories suggest either a Jahn-Teller distorted d 4 configuration [9,10] or a d 5 + h configuration with the hole tightly bound in a state similar to the Zhang-Rice polaron [11][12][13][14][15], but experiments remain inconclusive on the nature of the Mn 0 electronic configuration [2,16,17]. For Fe in GaN, even * hannes@ynu.ac.jp the existence of the Fe + charge state remains unclear [14,[18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Control of hole localization in magnetic semiconductors by axial strain

Raebiger

Bae

Echeverría‐Arrondo

et al. 2018

Phys. Rev. Materials

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Mn and Fe-doped GaN are widely studied prototype systems for hole-mediated magnetic semiconductors. The nature of the hole states around the Mn and Fe impurities, however, remains under debate. Our self-interaction corrected density-functional calculations show that the charge neutral Mn 0 and positively charged Fe + impurities have symmetry-broken d 5 + h ground states, in which the hole is trapped by one of the surrounding N atoms in a small polaron state. We further show that both systems also have a variety of other d 5 + h configurations, including symmetric, delocalized states, which may be stabilized by axial strain. This finding opens a pathway to promote long-range hole-mediated magnetic interactions by strain engineering and clarifies why highly strained thin-films samples often exhibit anomalous magnetic properties.

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Section: Introductionmentioning

confidence: 99%

Control of hole localization in magnetic semiconductors by axial strain

Raebiger

Bae

Echeverría‐Arrondo

et al. 2018

Phys. Rev. Materials

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“…The generalized firstprinciples spin-Fermion Hamiltonian of Ref. 50 provides an impurity potential which has both spin-dependent and spin-independent components. The assumption of ferromagnetism implies that we are underestimating the effects of disorder, since we only include chemical but not magnetic disorder.…”

Section: Resultsmentioning

confidence: 99%

“…To include superexchange we would need to redo the analysis in Ref. 50 without removing the Mn-d charge degrees of freedom. However, to determine localization in such an interacting and disordered multi-band model is a formidable task, beyond the scope of the current manuscript.…”

Section: Resultsmentioning

confidence: 99%

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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“…we obtain a half-metallic state. [12][13][14] But breaking the cubic symmetry and allowing for a Jahn-Teller distortion in combination with a correct treatment of the Coulomb repulsion in the d-shell opens up a gap of about 0.8 eV and leads to an insulating behavior. 15,16 The insulating state corresponds to a stable Mn 3+ state and no hole doping into the valence band in difference to the situation in GaAs:Mn.…”

Section: Introductionmentioning

confidence: 99%

“…22 And finally, even the Mn 3+ valency was recently questioned in a theoretical study. 14 It is a famous knowledge that Mg doping in GaN leads to hole carriers. The discovery of p-type GaN was a crucial step to develop the now well known white light emitting diodes and was re-compensated by the Nobel prize in 2014.…”

Section: Introductionmentioning

confidence: 99%

Exchange coupling and Mn valency in GaN doped with Mn and co-doped with Mg

et al. 2020

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We study 1 or 2 neighboring Mn impurities, as well as complexes of 1 Mn and 1 or 2 Mg ions in a 64 atoms supercell of GaN by means of density functional calculations. Taking into account the electron correlation in the local spin density approximation with explicit correction of the Hubbard term (the LSDA+U method) and full lattice relaxation we determine the nearest neighbor exchange J for a pair of Mn impurities. We find J to be ferromagnetic and of the order of about 18 meV in the HamiltonianĤ = −2Jˆ S1 ·ˆ S2. That J is only weakly influenced by the U parameter (varying between 2 and 8 eV) and by the lattice relaxation. From a detailed analysis of the magnetization density distribution we get hints for a ferromagnetic super-exchange mechanism. Also the Mn valence was found to be 3+ without any doubt in the absence of co-doping with Mg. Co-doping with Mg leads to a valence change to 4+ for 1 Mg and to 5+ for 2 Mg. We show that the valence change can already be concluded from a careful analysis of the density of states of GaN doped with Mn without any Mg.

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What is the Valence of Mn inGa1−xMnxN?

Cited by 14 publications

References 68 publications

Control of hole localization in magnetic semiconductors by axial strain

Control of hole localization in magnetic semiconductors by axial strain

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

Exchange coupling and Mn valency in GaN doped with Mn and co-doped with Mg

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