Wigner-Seitz approach to spin splitting

Guillaume, C. Benoît à la; Scalbert, D.; Dietl, T.

doi:10.1103/physrevb.46.9853

Cited by 76 publications

(85 citation statements)

References 19 publications

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“…We also note that only in the case of U =4.5 eV the linear interpolation presents the correct limit ∆E v → 0 for x → 0, while this is not found for the LSDA or for other values of U . Although simple multiple scattering corrections which reproduce the appropriate behaviour for x → 0 can be added to our analysis [15,41], this is an interesting result in itself. In fact the value of U =4.5 eV gives also the correct position of the Mn d states, and produces band structure that closely agrees with those calculated with our parameter free LDA-SIC method [20].…”

Section: B (Gamn)as: Magnetic Interactionmentioning

confidence: 99%

Different origins of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

2004

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The mechanism for the ferromagnetic order of (Ga,Mn)As and (Ga,Mn)N is extensively studied over a vast range of Mn concentrations. We calculate the electronic structures of these materials using density functional theory in both the local spin density approximation and the LDA+U scheme, that we have now implemented in the code SIESTA. For (Ga,Mn)As, the LDA+U approach leads to a hole mediated picture of the ferromagnetism, with an exchange constant N β= -2.8 eV. This is smaller than that obtained with LSDA, which overestimates the exchange coupling between Mn ions and the As p holes. In contrast, the ferromagnetism in wurtzite (Ga,Mn)N is caused by the double-exchange mechanism, since a hole of strong d character is found at the Fermi level in both the LSDA and the LDA+U approaches. In this case the coupling between the Mn ions decays rapidly with the Mn-Mn separation. This suggests a two phases picture of the ferromagnetic order in (Ga,Mn)N, with a robust ferromagnetic phase at large Mn concentration coexisting with a diluted weak ferromagnetic phase.

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Section: B (Gamn)as: Magnetic Interactionmentioning

confidence: 99%

Different origins of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

2004

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“…On going from antimonides to nitrides or from tellurides to oxides, the p−d hybridization increases. In the strong-coupling limit, the short-range part of the transition-metal ion (TM) potential may render the virtual-crystal approxi-mation (VCA) and molecular-field approximation invalid [67,75], leading to properties somewhat reminiscent of those specific to non-VCA alloys, like Ga(As,N) [76]. In particular, the short-range potential leads to a local admixture to extra atomic wave functions, which can produce modifications in optical and transport characteristics, such as an apparent change in carrier effective masses.…”

Section: Spatially Uniform Ferromagnetic Dmsmentioning

confidence: 99%

“…These materials exhibit characteristics specific to both charge transfer insulators and strongly correlated disordered metals. Moreover, complexities specific to strongly correlated systems coexist in DMS with features exhibited by heavily doped semiconductors and semiconductor alloys, such as the Anderson-Mott localization [9], defect generation by self-compensation mechanisms [46,65,66], and the breakdown of the virtual crystal approximation [67]. Nevertheless, the theory built on p−d Zener model of carrier-mediated ferromagnetism and on either Kohn-Luttinger's kp [64,65,68] or multi-orbital tight-binding [69][70][71] descriptions of the valence band in tetrahedrally coordinated semiconductors has qualitatively, and often quantitatively, described thermodynamic, micromagnetic, transport, and optical properties of DMS with delocalized holes [72][73][74], challenging competing theories.…”

Section: Spatially Uniform Ferromagnetic Dmsmentioning

confidence: 99%

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

Dietl

2007

Acta Phys. Pol. A

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In this paper the present understanding of the origin of ferromagnetic response that has been detected in a number of diluted magnetic semiconductors and diluted magnetic oxides at room temperature is outlined. It is argued that in these systems, owing to a typically small solubility of magnetic ions, crystallographic or chemical phase separation into regions with a large and a small concentration of magnetic component takes place. The ferromagnetic signatures then come from the regions with a large concentration of magnetic ions, which show non-zero spontaneous magnetization up to the blocking temperature, whose magnitude is proportional to the nanocrystal volume and magnetic anisotropy. Novel methods enabling a control of nano-assembling of magnetic nanocrystals in non-conducting matrices as well as possible functionalities of these spatially modulated magnetic systems are described. We also discuss phase separations into paramagnetic and ferromagnetic regions, which are driven by the Anderson-Mott localization and/or competing ferromagnetic and antiferromagnetic interactions. Finally, the question whether the high temperature ferromagnetism is possible in materials without magnetic ions is addressed.

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“…On going from antimonides to nitrides or from tellurides to oxides, the p-d hybridization increases. In the strong-coupling limit, the short-range part of the TM potential may render the virtual-crystal approximation and molecular-field approximation invalid (Benoit a la Guillaume, Scalbert and Dietl, 1992;Matsukura and Ohno, 2002), leading to properties somewhat reminiscent of those specific to alloys which cannot be described by the virtual crystal approximation, like Ga(As,N) (Wu, Shan and Walukiewicz, 2002). Here, dynamic mean-field approximation (DMFA) may capture relevant physics (Chattopadhyay, Das Sarma and Millis, 2001).…”

Section: P-d Zener Modelmentioning

confidence: 99%

“…These materials exhibit characteristics specific to both charge transfer insulators and strongly correlated disordered metals. Moreover, complexities specific to strongly correlated systems coexist in DMS with features exhibited by heavily doped semiconductors and semiconductor alloys, such as Anderson-Mott localization (Dietl, 1994), defect generation by self-compensation mechanisms (Dietl, Ohno and Matsukura, 2001;Mašek and Máca, 2001;Yu et al, 2002), and the breakdown of the virtual-crystal approximation (Benoità la Guillaume, Scalbert and Dietl, 1992). Nevertheless, the theory built on p-d Zener's model of carrier-mediated ferromagnetism and on either KohnLuttinger's kp (Dietl et al, 2000;Dietl, Ohno and Matsukura, 2001;Abolfath, Jungwirth, Brum and MacDonald, 2001) or multiorbital tight-binding (Vurgaftman and Meyer, 2001;Sankowski and Kacman, 2005;Timm and MacDonald, 2005) descriptions of the valence band in tetrahedrally coordinated semiconductors has qualitatively, and often quantitatively, described thermodynamic, micromagnetic, transport, and optical properties of DMS with delocalized holes Jungwirth et al, 2006a;Sankowski, Kacman, Majewski and Dietl, 2006a), challenging competing theories.…”

Section: Introductionmentioning

confidence: 99%

Diluted Ferromagnetic Semiconductors—Theoretical Aspects

Dietl

2007

Handbook of Magnetism and Advanced Magnetic Materials

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This chapter reviews theoretical understanding of ferromagnetic response that has been detected in diluted magnetic semiconductors (DMS). Particular attention is paid to those ferromagnetic DMS in which no precipitation of other crystallographic phases has been observed. It is argued that these materials can be divided into three categories. The first consists of (Ga,Mn)As, heavily doped p‐(Zn,Mn)Te, and related compounds. In these solid solutions, the theory built on p–d Zener's model of hole‐mediated ferromagnetism and on either the Kohn‐Luttinger kp theory or the multiorbital tight‐binding approach describes qualitatively, and often quantitatively, thermodynamic, micromagnetic, optical, and transport properties. Moreover, the understanding of these materials has provided a basis for the development of novel methods enabling magnetization manipulation and switching. To the second group, belong compounds in which a competition between long‐range ferromagnetic and short‐range antiferromagnetic interactions and/or the proximity of the localization boundary lead to an electronic nanoscale phase separation that results in characteristics similar to colossal magnetoresistance oxides. Finally, in a number of compounds a chemical nanoscale phase separation into the regions with small and large concentrations of the magnetic constituent is present. Methods of controlling the spinodal decomposition and possible functionalities of these systems are outlined.

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Wigner-Seitz approach to spin splitting

Cited by 76 publications

References 19 publications

Different origins of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

Different origins of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)N

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

Diluted Ferromagnetic Semiconductors—Theoretical Aspects

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