Erratum: Half-Metallic Ferromagnetism and Structural Stability of Zincblende Phases of the Transition-Metal Chalcogenides [Phys. Rev. Lett.<b>91</b>, 037204 (2003)]

Xie, Wenhui; Xu, Yawei; Liu, Bang-Gui; Pettifor, D. G.

doi:10.1103/physrevlett.91.219901

Cited by 114 publications

(157 citation statements)

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“…Table 1 shows best-fit parameters for each sample. Obtained Cr-Te bond lengths are 2.71 -2.73 Å, which is close the value expected from the lattice constant (6.29 Å) of hypothetical zinc-blende (ZB) CrTe obtained by density-functional calculations [7]. Obtained coordination numbers are close to 4, which coincide with that for substitutional Cr on Zn-site in ZnTe lattice and/or ZB CrTe.…”

Section: Methodssupporting

confidence: 60%

Fluorescence XAFS analysis of local structures in iodine-doped Zn_1-xCr_xTe

Ofuchi

Ishikawa

Zhang

et al. 2009

J. Phys.: Conf. Ser.

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Abstract. Geometric structures for II-VI diluted magnetic semiconductor iodine-doped Zn 1-x Cr x Te films (x = 0.05) grown by molecular-beam epitaxy with high-temperature ferromagnetism were investigated by using fluorescence x-ray absorption fine structure (XAFS) measurement in order to elucidate the relationship between the geometric structure and the magnetic properties. The XAFS analysis has revealed that the local structures around Cr atoms are dependent on the growth temperature. For the samples grown at 360 and 390 °C, the majority of Cr atoms are tetrahedrally coordinated to Te atoms, indicating the formation of substitutional Cr on Zn-site in ZnTe lattice and/or zinc-blende (ZB) CrTe. On the contrary, for the samples grown at 300 and 330 °C the additional formation of secondary phases such as CrTe compounds was suggested. Therefore, it is deduced that the formation of secondary phase such as Cr-Te compounds are related to the increase of Curie temperature. The XAFS analysis has also revealed that the local structures do not depend on the I concentration. For the samples with different I concentrations, the Cr atoms form substitutional Cr on Zn-site in ZnTe lattice and/or ZB CrTe, corresponding to the result of TEM measurement.

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Section: Methodssupporting

confidence: 60%

Fluorescence XAFS analysis of local structures in iodine-doped Zn_1-xCr_xTe

Ofuchi

Ishikawa

Zhang

et al. 2009

J. Phys.: Conf. Ser.

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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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“…However, from the theoretical point of view, first-principles studies indicate that ZB binary half metals are rarely stabilized by coherent epitaxy. Xie et al 14 compared density functional total energies of the bulk 3d transition-metal chalcogenides in ZB and NiAs-type structures and found a rather high energy for the metastable ZB CrAs. Zhao et al 15 performed a more accurate comparison, taking into account the tetragonal distortion in the films induced by the substrate.…”

mentioning

confidence: 99%

Stable structure and magnetic state of ultrathin CrAs films on GaAs(001): A density functional theory study

2010

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Density functional theory calculations using the pseudopotential-plane-wave approach are employed to investigate the structural and magnetic properties of epitaxial CrAs thin films on GaAs͑001͒. Motivated by recent reports of ferromagnetism in this system, we compare zinc-blende CrAs films ͑continuing the lattice structure of the GaAs substrate͒ and CrAs films with a bulklike orthorhombic structure epitaxially matched to three units of the GaAs͑001͒ lattice. We find that even for very thin films with three Cr layers the bulklike crystal structure is energetically more favorable than zinc-blende CrAs on GaAs͑001͒. CrAs films with orthorhombic structure, even if under epitaxial strain, preserve the antiferromagnetic order of CrAs bulk. In the light of our calculations, it appears likely that the magnetic hysteresis loop measured in ultrathin CrAs/GaAs͑001͒ films originates from uncompensated antiferromagnetic moments near the CrAs/GaAs interface. In conclusion, our results do not support earlier proposals that thick CrAs films could be employed as perfectly matched spin-injection electrode on GaAs. I. MOTIVATION AND BACKGROUNDSpin injection from a ferromagnet into a semiconductor is a major prerequisite for semiconductor spintronics. In recent years it has become clear that the efficiency of spin injection not only depends on the degree of spin polarization in the ferromagnet but the ferromagnet-semiconductor interface also plays a crucial role. Using electrodes fabricated from conventional ferromagnetic ͑FM͒ materials, such as Fe or Co, only a limited amount of spin-polarized current could be injected into GaAs. 1,2 As possible reasons, the conductivity mismatch in the metal and the ͑doped͒ semiconductor has been discussed 3 but the unsatisfactory results could also be due to technological problems in fabricating high-quality interfaces.As an alternative, Akinaga et al. 4 suggested to grow CrAs epitaxially, in the zinc-blende ͑ZB͒ structure, on GaAs. As advantages over conventional ferromagnetic electrodes, it has been pointed out that the use of a zinc-blende CrAs layer on GaAs not only avoids ͑possibly detrimental͒ interface states 5 but in addition zinc-blende CrAs is a half-metallic ferromagnet according to DFT calculations, i.e., it offers the highest possible spin polarization of 100%. By growing a superlattice of alternating CrAs and GaAs layers, Akinaga et al. managed to fabricate heterostructures showing ferromagnetic behavior at room temperature. Following this work, several research groups studied epitaxial CrAs films on GaAs, 6-11 and confirmed the ferromagnetic hysteresis of the samples. The saturation magnetization was found to correspond to about 2 B up to 3 B per Cr atom. However, the remanent magnetization was typically much lower, less than 10% of the saturation magnetization. Transmission electron microscopy ͑TEM͒ images of the samples demonstrated pseudomorphic growth of CrAs on GaAs, and most researchers claimed the formation of zinc-blende CrAs. However, Etgens et al., 12 using in situ refl...

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Erratum: Half-Metallic Ferromagnetism and Structural Stability of Zincblende Phases of the Transition-Metal Chalcogenides [Phys. Rev. Lett.91, 037204 (2003)]

Cited by 114 publications

References 0 publications

Fluorescence XAFS analysis of local structures in iodine-doped Zn_1-xCr_xTe

Fluorescence XAFS analysis of local structures in iodine-doped Zn_1-xCr_xTe

Are half-metallic ferromagnets half metals? (invited)

Stable structure and magnetic state of ultrathin CrAs films on GaAs(001): A density functional theory study

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Erratum: Half-Metallic Ferromagnetism and Structural Stability of Zincblende Phases of the Transition-Metal Chalcogenides [Phys. Rev. Lett.91, 037204 (2003)]

Cited by 114 publications

References 0 publications

Fluorescence XAFS analysis of local structures in iodine-doped Zn1-xCrxTe

Fluorescence XAFS analysis of local structures in iodine-doped Zn1-xCrxTe

Are half-metallic ferromagnets half metals? (invited)

Stable structure and magnetic state of ultrathin CrAs films on GaAs(001): A density functional theory study

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Product

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Fluorescence XAFS analysis of local structures in iodine-doped Zn_1-xCr_xTe

Fluorescence XAFS analysis of local structures in iodine-doped Zn_1-xCr_xTe