Anisotropic Magnetoresistance Effects in Fe, Co, Ni, Fe<sub>4</sub>N, and Half-Metallic Ferromagnet: A Systematic Analysis

Kokado, Satoshi; Tsunoda, Masakiyo; Harigaya, Kikuo; Sakuma, Atsushi

doi:10.1143/jpsj.81.024705

Cited by 183 publications

(212 citation statements)

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“…The calculated values of S and α are shown in the inset of Very recently, Kokado et al [18] have systematically investigated the sign of the anisotropy magnetoresisetnce (AMR) of ferromagnetic materials. As a result, they found that, for half-metallic ferromagnets, the dominant scattering is s↑→d↑or s↓→d↓, which cause the sign of the AMR tends to be negative [19,20].…”

Section: Resultsmentioning

confidence: 99%

Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1−xCrxSi

Liu

et al. 2013

Journal of Magnetism and Magnetic Materials

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Abstract:In this paper, we investigate the half-metallicity of Heusler alloys Keyword: half-metallicity; Heusler alloys; anisotropy magnetoresistance 1.IntroductionHalf-metallic ferromagnets were discovered by theory with the prediction of 100% spin polarization [1,2], in which the majority-spin electrons are metallic, whereas the minority-spin electrons are semiconducting. Since the first prediction of half-metallic ferromagnet in Heusler compounds in 1983 by de. Groot [3], several Heusler series that possess half-metallic properties have been experimentally realized [4][5][6]. Full-Heusler compounds are usually presented as general formula X 2 YZ, where X and Y are transition elements, Z represents main group element. The cubic unit cell consists of four interpenetrating face-centered-cubic (fcc) sublattices, two of which are occupied by identical X atoms and the other two by Y and Z atoms, respectively [7]. Because of high Curie temperature, Co-based Heusler compounds are considered as the most promising candidates for half-metallic ferromagnets working at room temperature [8,9]. However, Co-based Heusler compounds have a serious inadequacy that a high L2 1 degree of order is necessary to present a high spin polarization. For example, the recent experiments found that, in sputtered Co 2 MnSi Heusler films, a few degree of atomic disorder between Co and Mn will cause a largely reducing of the spin polarization [10]. On the other hand, the thermal excitation and spin-flip scattering can also destroy the half-metallitity in Co-based Heusler alloys. To avoid thermal excitation and spin-flip scattering of electrons to the conduction sub-band, Benjamin Bakle et al. [12] found that Fe-based Heusler alloys Fe 2 CoSi and Fe 2 CrSi are two typical half-metallic ferromagnets. They also pointed out that the half-metallitity of these Fe-based Heusler alloys is insensitive to atomic disorder. However, the Fermi level of Fe 2 CoSi and Fe 2 CrSi locate at the edge of valance and conductance bands, respectively. In this paper, using the first principles calculations, we investigate the band structures of a series Fe 2 Co 1-x Cr x Si Heusler compounds, to find the most stable half-metallic ferromagnets. The in-plane anisotropic magnetoresitance (AMR) experiments were further performed to verify the half-metallicity in this series. ExperimentalFe 2 Co 1-x Cr x Si (x=0.0, 0.25, 0.5, 0.75, 1) ingots were prepared by arc-melting under an Ar atmosphere. Melting was repeated several times to obtain chemically homogenous ingots. Because the flaked sample for the measurements of AMR cannot be obtained by arc-melting, the melt-spinning method was utilized to make small metal sheets from the obtained ingots. The thickness of the ribbon samples used in this work is roughly around 46 μm. Structural examination was measured by x-ray diffraction (XRD) with Cu-Ka radiation. The AMR effect in all samples was measured by the standard four-terminal method in Physical Property Measurement System (PPMS). A superconducting quantum interference dev...

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Section: Resultsmentioning

confidence: 99%

Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1−xCrxSi

Liu

et al. 2013

Journal of Magnetism and Magnetic Materials

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“…Existing theoretical approaches to the AMR in metals and alloys are based on inclusion of the SO interaction in the lowest-order perturbation expansion. 42,47,48 However, the validity of such schemes for the Ni-rich alloys is limited due to the well-known fact that the SO interaction increases the resistivity by a factor of two or more as compared to the resistivity within the two current model.…”

Section: A Amr In Random Fcc Ni-based Alloysmentioning

confidence: 99%

Ab initiotheory of galvanomagnetic phenomena in ferromagnetic metals and disordered alloys

Turek

Kudrnovský²,

Drchal³

2012

Phys. Rev. B

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We present an ab initio theory of transport quantities of metallic ferromagnets developed in the framework of the fully relativistic tight-binding linear muffin-tin orbital method. The approach is based on the Kubo-Středa formula for the conductivity tensor, on the coherent potential approximation for random alloys, and on the concept of interatomic electron transport. The developed formalism is applied to pure 3d transition metals (Fe, Co, Ni) and to random Ni-based ferromagnetic alloys (Ni-Fe, Ni-Co, Ni-Mn). High values of the anisotropic magnetoresistance (AMR), found for Ni-rich alloys, are explained by a negligible disorder in the majority spin channel while a change of the sign of the anomalous Hall effect (AHE) on alloying is interpreted as a band-filling effect without a direct relation to the high AMR. The influence of disorder on the AHE in concentrated alloys is investigated as well.

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“…Anisotropic magnetoresistance (AMR) is a direct consequence of s-d scattering in ferromagnets and is very sensitive to the distribution of the density of states at the Fermi energy [6], taking on a negative value for half metals [7]. AMR was explained by Smit [8] by the introduction of the spin-orbit interaction (SOI) through a perturbation that is suggested to result in an unequal distribution of d states, such that there exists more orbitals parallel to the magnetization rather than perpendicular to it, resulting in a shorter and longer mean-free path, respectively.…”

Section: Introductionmentioning

confidence: 99%

Enhanced electron-magnon scattering in ferromagnetic thin films and the breakdown of the Mott two-current model

2014

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Electron-magnon spin-flip scattering in thin films was studied by investigating the thickness dependence of the anisotropic magnetoresistance (AMR) effect and spin-wave stiffness. The absolute resistivity change due to the AMR effect ( ρ) in Ni, Ni:V, and Ni:Cr doped films reduced with film thickness. This loss of AMR is due to enhanced spin-flip scattering, dropping at the same thickness irrespective of dopant. The spin-wave stiffness reduced at the same thickness, confirming enhanced electron-magnon spin-flip scattering. The AMR ratio was fitted with a simple model, in which thickness dependence was included in a spin mixing resistivity term. This analysis gives insight into the fundamental contribution of magnon scattering to the resistivity in thin films, which ultimately has relevance to spin coherence in spintronic devices.

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Anisotropic Magnetoresistance Effects in Fe, Co, Ni, Fe₄N, and Half-Metallic Ferromagnet: A Systematic Analysis

Cited by 183 publications

References 44 publications

Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1−xCrxSi

Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1−xCrxSi

Ab initiotheory of galvanomagnetic phenomena in ferromagnetic metals and disordered alloys

Enhanced electron-magnon scattering in ferromagnetic thin films and the breakdown of the Mott two-current model

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Anisotropic Magnetoresistance Effects in Fe, Co, Ni, Fe4N, and Half-Metallic Ferromagnet: A Systematic Analysis

Cited by 183 publications

References 44 publications

Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1−xCrxSi

Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1−xCrxSi

Ab initiotheory of galvanomagnetic phenomena in ferromagnetic metals and disordered alloys

Enhanced electron-magnon scattering in ferromagnetic thin films and the breakdown of the Mott two-current model

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Anisotropic Magnetoresistance Effects in Fe, Co, Ni, Fe₄N, and Half-Metallic Ferromagnet: A Systematic Analysis