Hole-Mediated Stabilization of Cubic GaN

Dalpian, Gustavo M.; Wei, Su‐Huai

doi:10.1103/physrevlett.93.216401

Cited by 33 publications

(19 citation statements)

References 24 publications

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“…However, in many situations, it is desirable to keep the ZB structure, to take advantage of its better electronic and transport properties [53]. In this case, we suggest that to increase the spin-splitting of the conduction band, allowing the electron-induced stabilization of ferromagnetism, one can introduce rare-earth (RE) elements as magnetic impurities.…”

Section: Rare Earth Dopingmentioning

confidence: 99%

Carrier‐mediated stabilization of ferromagnetism in semiconductors: holes and electrons

Dalpian¹,

Wei

2006

Physica Status Solidi (b)

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PACS 71. 75.50.Pp Band structure models are proposed to help understand carrier-induced ferromagnetism in diluted magnetic semiconductors. We describe both hole-and electron-mediated ferromagnetism. For hole-mediated ferromagnetism, we show that there are two distinct mechanisms related to the stabilization of ferromagnetism. The difference between them is related to the position of the impurity d levels with respect to the valence band edge. If the impurity states are in the band gap, ferromagnetism can be explained by double exchange, which is related to the direct coupling between the impurity levels, whereas if the filled impurity states are below the VBM, ferromagnetism can be explained by the Zener model, which is related to the coupling between the impurity d levels and the host valence p states. In both cases, it is necessary to have holes, either free or localized, to stabilize the ferromagnetism. Our model successfully explains the ground state magnetic configuration of CdMnTe, GaMnAs, ZnMnO, and GaMnN. An extension of our model can also successfully explain the intriguing behavior of GaMnN. We show that at low Mn concentration, its ground state is FM, although AFM can be stabilized by increasing the Mn concentration, applying pressure, or by compensating the holes. For electron-mediated ferromagnetism, we point out that it is necessary first to increase the exchange splitting of the conduction band. This can be done by reducing the symmetry of the system, by quantum confinement, or by changing the magnetic impurities from transition metals to rare earths. Our results also clarify some issues related to experimental works, such as the negative exchange splitting of the conduction band in GaMnAs quantum wells and the stabilization of ferromagnetism in GaGdN.

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Section: Rare Earth Dopingmentioning

confidence: 99%

Carrier‐mediated stabilization of ferromagnetism in semiconductors: holes and electrons

Dalpian¹,

Wei

2006

Physica Status Solidi (b)

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“…81,93 Although the two structures have different space groups, they are in fact very similar. 93,94 They have the same local tetrahedral environment and start to differ only in their third-nearest-neighbor atomic arrangement. The cubic phase is described by its lattice constant a ZB .…”

Section: Structural Modelmentioning

confidence: 99%

X-ray magnetic dichroism in III-V diluted magnetic semiconductors: First-principles calculations

2010

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The electronic structure of the ͑Ga,Mn͒As, ͑Ga,Mn͒N, and ͑Ga,Gd͒N, diluted magnetic semiconductors ͑DMSs͒ were investigated theoretically from first principles, using the fully relativistic Dirac linear muffin-tin orbital band-structure method. The electronic structure is obtained with the local spin-density approximation ͑LSDA͒, as well as the LSDA+ U method. The x-ray magnetic circular and linear dichroism ͑XMCD and XMLD͒ spectra at the Mn, As, Ga, and N K and Gd, Mn, As, and Ga L 2,3 edges were investigated theoretically from first principles. The origin of the XMCD spectra in these compounds was examined. The effect of interstitial Mn atoms was found to be crucial for the x-ray magnetic dichroism at the Mn and As K and L 2,3 edges in the ͑Ga,Mn͒As DMS. The influence of the exchange splitting and spin-orbit coupling strength on each of the constituent atoms were furthermore analyzed. The orientation dependence of the XMCD and XMLD at the Mn L 2,3 edges in the ͑Ga,Mn͒As DMS was investigated by calculating the XMCD and XMLD spectra for the ͗001͘ and ͗110͘ magnetization axis. We found a quite small anisotropy in the XMCD and a giant anisotropy in the XMLD at the Mn L 2,3 edges. The exchange splitting of the initial Mn 2p core level was found to be responsible for huge magnetocrystalline anisotropy of the XMLD at the Mn L 2,3 edges. The calculated results are compared with available experimental data.

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“…For this, we used the standard approach [8], where the band offset is given by Table 1 we show the calculated energy difference variation dE ZB-WZ /dx, where x is the concentration of the dopant. This was calculated by sampling the energy differences for different impurity concentrations.…”

Section: Resultsmentioning

confidence: 99%