Nonquasiparticle states in the half-metallic ferromagnet NiMnSb

Chioncel, Liviu; Katsnelson, M. I.; Groot, de Robert; Lichtenstein, A. I.

doi:10.1103/physrevb.68.144425

Cited by 107 publications

(168 citation statements)

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“…19,20). To underline the importance of complete LDA+DMFT self-consistency we mention that the first successful attempt to combine the DMFT with LDA charge selfconsistency gave an important insight into a long-standing problem of phase diagram and localization in f-electron systems [17,18] and has been used also to describe correlation effects in half-metallic ferromagnetic materials like NiMnSb [21]. As an alternative to the above mentioned band structure methods, accurate self-consistent methods for solving the local Kohn-Sham equations based on LDA in terms of Green's functions have been developed within the multiple scattering theory (KKR-method) [22,23,24,25].…”

Section: Formulation Of the Problemmentioning

confidence: 99%

Multiple-scattering formalism for correlated systems: A KKR-DMFT approach

Minář¹,

Chioncel

Perlov³

et al. 2005

Phys. Rev. B

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We present a charge and self-energy self-consistent computational scheme for correlated systems based on the Korringa-Kohn-Rostoker (KKR) multiple scattering theory with the many-body effects described by the means of dynamical mean field theory (DMFT). The corresponding local multi-orbital and energy dependent self-energy is included into the set of radial differential equations for the single-site wave functions. The KKR Green's function is written in terms of the multiple scattering path operator, the later one being evaluated using the single-site solution for the t-matrix that in turn is determined by the wave functions. An appealing feature of this approach is that it allows to consider local quantum and disorder fluctuations on the same footing.Within the Coherent Potential Approximation (CPA) the correlated atoms are placed into a combined effective medium determined by the dynamical mean field theory (DMFT) self-consistency condition. Results of corresponding calculations for pure Fe, Ni and Fe x Ni 1−x alloys are presented.

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Section: Formulation Of the Problemmentioning

confidence: 99%

Multiple-scattering formalism for correlated systems: A KKR-DMFT approach

Minář¹,

Chioncel

Perlov³

et al. 2005

Phys. Rev. B

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130

150

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“…Several explanations have been suggested in the literature. Chioncel et al 19,20 discussed the depolarization at finite temperature in terms of strong correlation effects out of reach of standard electronic structure methods. Recently such calculations were suggested to show that strong electron correlation effects suppress half-metallicity also at 0 K. 21 However, those calculations failed to reproduce experimental magnetic moments close to 4.0 B , making their quantitative predictions questionable.…”

Section: Introductionmentioning

confidence: 99%

“…Doping is also likely to have an impact on strong electron correlation effects. 19,20 However, if a high concentration of Mn replacing Ni is desired in the material, careful considerations must be made as regards the structural stability of the half-Heusler phase. The end compound Mn 2 Sb, corresponding to all Ni atoms being replaced by Mn, crystallizes in the tetragonal C38 structure ͑Cu 2 Sb-type͒ and is a normal metal.…”

Section: Introductionmentioning

confidence: 99%

Ab initio calculations and synthesis of the off-stoichiometric half-Heusler phase Ni1−xMn1+xSb

Ekholm

Larsson

Alling

et al. 2010

Journal of Applied Physics

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We perform a combined theoretical and experimental study of the phase stability and magnetism of the off-stoichiometric Ni 1−x Mn 1+x Sb in the half-Heusler crystal phase. Our work is motivated by the need for strategies to engineer the magnetism of potentially half-metallic materials, such as NiMnSb, for improved performance at elevated temperatures. By means of ab initio calculations we investigate Ni 1−x Mn 1+x Sb over the whole composition range 0 Յ x Յ 1 of Ni replacing Mn and show that at relevant temperatures, the half-Heusler phase should be thermodynamically stable up to at least x = 0.20 with respect to the competing C38 structure of Mn 2 Sb. Furthermore we find that half-Heusler Ni 1−x Mn 1+x Sb retains half-metallic band structure over the whole concentration range and that the magnetic moments of substitutional Mn Ni atoms display magnetic exchange interactions an order of magnitude larger than the Ni-Mn interaction in NiMnSb. We also demonstrate experimentally that the alloys indeed can be created by synthesizing off-stoichiometric Ni 1−x Mn 1+x Sb films on MgO substrates by means of magnetron sputtering.

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“…22 Moreover taking into account also the reconstruction at the surfaces and interfaces can have an important effect on their properties. 26 Finally we should note that several other aspects of NiMnSb have been studied using first-principles calculations like the exchange constants and Curie temperatures, 27,28,29 the quasiparticle states 30 and the dynamical effects, 31 the defects and doping, 32,33,34 the structural stability, 35,36 the effect of spin-orbit coupling, 37 the fit of model Hamiltonians to describe NiMnSb, 38,39 orbital magnetism, 40 the pressure and thermal expansion effects, 41 the temperature effect 42 and the magneto-optical properties. 43,44 The half-metallic character of NiMnSb in single crystals has been well-established experimentally.…”

Section: Introductionmentioning

confidence: 99%

Ab initio electronic and magnetic properties of half-metallic NiCrSi and NiMnSi Heusler alloys: The role of defects and interfaces

Galanakis

Özdoğan

Şaşıoğlu

2008

Journal of Applied Physics

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Using state-of-the-art first-principles calculations we study the properties of the ferromagnetic Heusler compounds NiYSi where Y stands for V, Cr or Mn. NiCrSi and NiMnSi contrary to NiVSi are half-metallic at their equilibrium lattice constant exhibiting integer values of the total spin magnetic moment and thus we concentrate on these two alloys. The minority-spin gap has the same characteristics as for the well-known NiMnSb alloy being around ∼1 eV. Upon tetragonalization the gap is present in the density of states even for expansion or contraction of the out-of-plane lattice parameter by 5%. The Cr-Cr and Mn-Mn interactions make ferromagnetism extremely stable and the Curie temperature exceeds 1000 K for NiMnSi. Surface and interfaces with GaP, ZnS and Si semiconductors are not half-metallic but in the case of NiCrSi the Ni-based contacts present spinpolarization at the Fermi level over 90%. Finally, we show that there are two cases of defects and atomic-swaps. The first-ones which involve the Cr(Mn) and Si atoms induce states at the edges of the gap which persists for a moderate-concentration of defects. Defects involving Ni atoms induce states localized within the gap completely destroying the half-metallicity. Based on single-impurity calculations we associate these states to the symmetry of the crystal.

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Nonquasiparticle states in the half-metallic ferromagnet NiMnSb

Cited by 107 publications

References 50 publications

Multiple-scattering formalism for correlated systems: A KKR-DMFT approach

Multiple-scattering formalism for correlated systems: A KKR-DMFT approach

Ab initio calculations and synthesis of the off-stoichiometric half-Heusler phase Ni1−xMn1+xSb

Ab initio electronic and magnetic properties of half-metallic NiCrSi and NiMnSi Heusler alloys: The role of defects and interfaces

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