Jahn-Teller distortion and ferromagnetism in the dilute magnetic semiconductors GaAs:Mn and cubic GaN:Mn

Luo, Xuan; Martin, Richard M.

doi:10.1103/physrevb.72.035212

Cited by 42 publications

(33 citation statements)

References 66 publications

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“…One thus expects a strong local Jahn-Teller instability toward splitting the degeneracy into 2 + 1. Indeed, the Jahn-Teller instability has been found in previous studies [55,56]. It is easier to describe this local physics using an "effective" d 4 picture.…”

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What is the Valence of Mn inGa1−xMnxN?

et al. 2015

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We investigate the current debate on the Mn valence in Ga1−xMnxN, a diluted magnetic semiconductor (DMSs) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to 2+ (d 5 ), but in a mixed spin configuration with average magnetic moments of 4µB. By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: 1) an effective d 4 picture ideal for local physics, and 2) an effective d 5 picture suitable for extended properties. In the latter, our results further reveal a few novel physical effects, and pave the way for future realistic studies of magnetism. Our study not only resolves one of the outstanding key controversies of the field, but also exemplifies the general need for multiple effective descriptions to account for the rich low-energy physics in many-body systems in general.

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What is the Valence of Mn inGa1−xMnxN?

et al. 2015

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“…We obtained a value of 1.9 eV comparing notably better with experiment (1.8±0.2 eV [37]) than PBE calculations (1.6 eV). In order to test the predictive capability of the procedure, we have repeated the calculations for Mn Ga in GaAs, for which Mn is experimentally found in a d 5 configuration [36]. In this case, the splitting of the t 2 states drops to ∼ 0.2 eV, and no Jahn-Teller effect is theoretically found using HSE or experimentally expected [36].…”

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confidence: 99%

“…In order to test the predictive capability of the procedure, we have repeated the calculations for Mn Ga in GaAs, for which Mn is experimentally found in a d 5 configuration [36]. In this case, the splitting of the t 2 states drops to ∼ 0.2 eV, and no Jahn-Teller effect is theoretically found using HSE or experimentally expected [36]. Furthermore, the HSE band structure for Mn in GaAs (Fig.…”

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Unraveling the Jahn-Teller effect in Mn-doped GaN using the Heyd-Scuseria-Ernzerhof hybrid functional

2009

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We present an ab-initio study of the Mn substitution for Ga in GaN using the Heyd-ScuseriaErnzerhof hybrid functional (HSE). Contrary to semi-local functionals, the majority Mn t2 manifold splits into an occupied doublet and an unoccupied singlet well above the Fermi-level resulting in an insulating groundstate, which is further stabilized by a sizeable Jahn-Teller distortion. The predictions are confirmed using GW calculations and are in agreement with experiment. A transition from a localized to a delocalized Mn hole state is predicted from GaN to GaAs.Semiconductor based spintronics aims to develop hybrid devices that could perform all three operations, logic, communications and storage within the same materials technology [1]. Dilute Magnetic Semiconductors (DMSs) represent the most promising materials, and undoubtedly, transition metal doped III-V semiconductors are presently the workhorse for spintronics [2].Ab-initio simulations based on density functional theory have played an important role in investigating the physics of DMSs [3,4]. Nevertheless, the theoretical understanding has been hindered by the well-known deficiencies of the spin-polarized local density approximation (SLDA) and generalized gradient approximation (SGGA) to the exchange-correlation functional [5]: the non-locality of the screened exchange interaction is not taken into account and the electrostatic self-interaction is not entirely compensated. This lack of compensation causes fairly large errors for localized states, e.g. the Mn d states. It destabilizes the orbitals and decreases their binding energy, leading to an over-delocalization of the charge density [6]. Another closely related issue is that the Kohn-Sham gap is usually a factor 2-3 smaller than the fundamental gap of the solid [5]. Whenever the energy position of the defect level with respect to the Valence Band Maximum (VBM) is comparable with the KohnSham gap, e.g. deep acceptor levels introduced by substitutional Mn in GaN (Mn Ga ) [7], the calculation of the thermodynamic transition levels becomes difficult, since all predicted thermodynamic transition levels are strictly bound by the Kohn-Sham one electron gap. Although the underestimation of the one electron gap would even occur for the exact Kohn-Sham functional, discontinuities in the potential upon adding or removing electrons correct for this error [5,8]. For approximate functionals, which lack any such discontinuities-this includes all available semi-local and hybrid functionals -agreement between the Kohn-Sham gap and experimental fundamental gap is a prerequisite for modelling thermodynamic transition levels and band structure related properties [5].Hybrid Hartree-Fock density functionals[9] overcome the two limitations discussed above to a large extend [5]. brid functional[10] to study the Mn impurity in a GaN semiconductor host. Extensive studies of the performance of the HSE functional in solid state systems can be found in Refs. 11,12,13, unequivocally showing that hybrid functionals outperform semi-local ...

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“…Interests are further caused by the prediction of ferromagnetism at room temperature and even above in these materials [2][3][4]. Of the established DMSs, Mndoped GaN films are predicted to have the higher Curie temperatures (T C ) above room temperature [5] and many efforts involving the controlled fabrication of these materials as well as to explore the characterization and their physical properties have been developed [6][7][8]. It has been suggested that the ferromagnetism (FM) in (Ga,Mn)N could arise from the formation of magnetic clusters [9].…”

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confidence: 99%

Mn clusterisation in

Wang

Zhang

Wang

et al. 2009

Solid State Communications

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Local structure of Mn atoms in Ga1-xMnxN has been investigated by the Mn L3 edge x-ray absorption spectrum (XAS) at total electron yield mode, which preferentially looks at atoms near the surface. A modeling defects configuration, the Mn5 micro-clusters complexed with substitutional MnGa and interstitial MnI is found for the higher Mn doping concentration.This new configuration is also confirmed by the total energy calculations.

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Jahn-Teller distortion and ferromagnetism in the dilute magnetic semiconductors GaAs:Mn and cubic GaN:Mn

Cited by 42 publications

References 66 publications

What is the Valence of Mn inGa1−xMnxN?

What is the Valence of Mn inGa1−xMnxN?

Unraveling the Jahn-Teller effect in Mn-doped GaN using the Heyd-Scuseria-Ernzerhof hybrid functional

Mn clusterisation in

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