Positron-annihilation study of the half-metallic ferromagnet NiMnSb: Theory

Hanssen, K. E. H. M.; Mijnarends, P.E.

doi:10.1103/physrevb.34.5009

Cited by 122 publications

(66 citation statements)

References 20 publications

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“…Also PtMnSb [8,9] and CoMnSb [10] have been predicted to be half-ferromagnets. Infrared absorption [11] and spinpolarized positron-annihilation [12] experiments have verified the half-ferromagnetic character of bulk NiMnSb. There is also ellipsometric evidence of the spin-down gap for PtMnSb [13].…”

Section: Introductionmentioning

confidence: 94%

Surface properties of the half-and full-Heusler alloys

Galanakis

2002

J. Phys.: Condens. Matter

233

166

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Abstract. Using a full-potential ab-initio technique I study the electronic and magnetic properties of the (001) surfaces of the half-Heusler alloys, NiMnSb, CoMnSb and PtMnSb and of the full-Heusler alloys Co 2 MnGe, Co 2 MnSi and Co 2 CrAl. The MnSb terminated surfaces of the half-Heusler compounds present properties similar to the bulk compounds and, although the half-metallicity is lost, an important spinpolarisation at the Fermi level. In contrast to this the Ni terminated surface shows an almost zero net spin-polarisation. While the bulk Co 2 MnGe and Co 2 MnSi are almost half-ferromagnetic, their surfaces lose the half-metallic character and the net spin-polarisation at the Fermi level is close to zero. Contrary to these compounds the CrAl terminated (001) surface of Co 2 CrAl shows a spin polarisation of about 84%.

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Section: Introductionmentioning

confidence: 94%

Surface properties of the half-and full-Heusler alloys

Galanakis

2002

J. Phys.: Condens. Matter

233

166

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“…Several other studies were performed on the stability of the minority-spin band-gap which was found to be stable under hydrostatic pressure and tetragonalization [12] or a small disorder [13] but the exchange of the atoms occupying the different sublattices completely destroys the gap [14]. Experiments seem to well establish the half-metallicity in the case of NiMnSb single crystals [15,16] or away from the surface in the case of thick films [17].…”

Section: Introductionmentioning

confidence: 99%

Structural and magnetic properties of the (001) and (111) surfaces of the half-metal NiMnSb

Galanakis

Bihlmayer

Blügel

2005

J. Phys.: Condens. Matter

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Structural and magnetic properties of the (001) and (111) Abstract. Using the full potential linearised augmented planewave method we study the electronic and magnetic properties of the (001) and (111) surfaces of the half-metallic Heusler alloy NiMnSb from first-principles. We take into account all possible surface terminations including relaxations of these surfaces. Special attention is paid to the spin-polarization at the Fermi level which governs the spin-injection from such a metal into a semiconductor. In general, these surfaces lose the half-metallic character of the bulk NiMnSb, but for the (111) surfaces this loss is more pronounced. Although structural optimization does not change these features qualitatively, specifically for the (111) surfaces relaxations can compensate much of the spin-polarization at the Fermi surface that has been lost upon formation of the surface.

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“…[1][2][3] The proposal that there might exist such half-metallic ferromagnetic materials with 100% zero-temperature spin polarization at the Fermi level has quite a long history 4 -8 dating back to de Groot. 5,6,8 Among the most cited candidates for 100% spin polarization are the semi-Heusler alloys ͑NiMnSb͒, [5][6][7][8][9][10][11][12] ''full'' Heusler alloys, [12][13][14] zinc-blende structure materials, [15][16][17] 4,27 Practical electronic devices that exploit the spin as well as the charge of the electron, 28,29 including nonvolatile magnetic random-access memory elements, 29,30 operate at nonzero temperatures, ideally at or above room temperature. Unfortunately, many potential half-metallic systems exhibit dramatic decreases in spin polarization and junction magnetoresistance well below room temperature, as discussed below.…”

Section: Introductionmentioning

confidence: 99%

Are half-metallic ferromagnets half metals? (invited)

Dowben

Skomski

2004

Journal of Applied Physics

133

116

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Several classes of materials are currently under investigation as potential high-spin-polarization materials. Unfortunately, the proposed half-metallic materials, including the semi-Heusler alloys, the manganese perovskites, and the ''simpler'' oxides such as chromium dioxide and magnetite, suffer from fundamental limitations. First, the postulated half-metallic systems lose their full (T ϭ0) spin polarization at finite temperatures and, second, surfaces, interfaces, and structural inhomogenities destroy the complete spin polarization of half-metallic systems even at zero temperature. In a strict sense, half-metallic ferromagnetism is limited to zero temperature since magnon and phonon effects lead to reductions in polarization at finite temperatures.

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Positron-annihilation study of the half-metallic ferromagnet NiMnSb: Theory

Cited by 122 publications

References 20 publications

Surface properties of the half-and full-Heusler alloys

Surface properties of the half-and full-Heusler alloys

Structural and magnetic properties of the (001) and (111) surfaces of the half-metal NiMnSb

Are half-metallic ferromagnets half metals? (invited)

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