High spin polarization in all 3d-metallic Heusler compounds: The case of Fe2CrZ and Co2CrZ (Z=Sc,Ti,V) (original) (raw)
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Magnetic and Structural Properties of Heusler Compounds with 27.8 Valence Electrons
Co 2 -based Heusler compounds with 27.8 valence electrons exhibit an exceptional electronic structure that makes them interesting materials for the application in spintronics. Co 2 Cr 0.6 Fe 0.4 Al is the most prominent example of this particular family of compounds. In this article new materials of this class are tested with respect to their structural and magnetic properties. X-ray diffraction, Mössbauer spectroscopy, energy dispersive X-ray spectroscopy, and SQUID magnetometry were carried out to characterize the compounds. The use of Co 2 Fe 0.45 Ti 0.55 Ge as a new material in spintronic devices is suggested.
Journal of Physics: Condensed Matter, 2011
Sb) are of large interest due to their potential ferrimagnetic properties and high spin polarization. Here, we present calculations of the structural and magnetic properties of these materials. Their magnetic moment follows the Slater-Pauling rule m = N V − 24. None of them is actually a perfect half-metallic ferrimagnet, but some exhibit more than 90% spin polarization and Curie temperatures well above room temperature. The exchange interactions are complex, direct and indirect exchange contributions are identified. The Curie temperature scales with the total magnetic moment, and it has a positive pressure dependence. The role of the Z element is investigated: it influences the properties of the compounds mainly via its valence electron number and its atomic radius, which determines the lattice parameter. Based on these results, Mn 2 TiSi, Mn 2 TiGe, and Mn 2 TiSn are proposed as candidates for spintronic applications.
First-principles investigation of half-metallic ferromagnetism of half-Heusler compounds XYZ
Journal of Magnetism and Magnetic Materials, 2014
and Sb) using the ab initio density functional theory calculations. Nine half-metals with half-Heusler structure have been predicted with the half-metallic gap of 0.07-0.67 eV. The calculations show that the formation energies for these nine half-Heusler compounds range from-1.32 to-0.12 eV/f.u., and for CoCrSi, CoCrGe, CoFeGe, CoMnSi, CoMnGe, FeMnGe and FeMnAs, the total energy differences between the half-Heusler structure and the corresponding ground-state structure are small (0.07-0.76 eV/f.u.), thus it is expected that they would be realized in the form of thin films under metastable conditions for spintronic applications. The stability of the half-metallicity of CoCrGe and FeMnAs to the lattice distortion is also investigated in detail.
International Journal of …, 2012
The structural optimization was followed by the calculation of electronic structure and magnetic properties on Co 2 CrAl and Co 2 CrGa. The structure optimization was based on generalized gradient approximation (GGA). The calculation of electronic structure was based on full potential linear augmented plane wave (FPLAPW) method within local spin density approximation (LSDA). We studied the electronic structure and magnetic properties. Results of density of states (DOS) and band structures shows that Co 2 CrAl and Co 2 CrGa are half-metallic ferromagnets (HMFS). The calculated magnetic moments of Co 2 CrAl and Co 2 CrGa are 2.915 and 3.075 µ B , respectively. We have calculated the onsite d-d coulomb and exchange interaction (U ) For 3d elements like Co and Cr. The strongly localized d states were treated with LSDA+U method.
New materials with high spin polarization: half-metallic Heusler compounds
Journal of Physics D: Applied Physics, 2007
The development of magnetic Heusler compounds, specifically designed as materials for spintronic applications, has made tremendous progress in the very recent past . Heusler compounds can be made as half-metals, showing a high spin polarization of the conduction electrons of up to 100% [1]. These materials are exceptionally well suited for applications in magnetic tunnel junctions acting, for example, as sensors for magnetic fields. The tunnelling magneto-resistance (TMR) effect is the relative change in the electrical resistance upon application of a small magnetic field. Tunnel junctions with a TMR effect of 580% at 4 K were reported by the group of Miyazaki and Ando [1], consisting of two Co 2 MnSi Heusler electrodes. High Curie temperatures were found in Co 2 Heusler compounds with values up to 1120 K in Co 2 FeSi [2]. The latest results are for a TMR device made from the Co 2 FeAl 0.5 Si 0.5 Heusler compound and working at room temperature with a TMR effect of 174% .
Electronic structure and magnetism in doped semiconducting half-Heusler compounds
Journal of Physics: Condensed Matter, 2005
We have studied in details the electronic structure and magnetism in M (Mn and Cr) doped semiconducting half-Heusler compounds FeVSb, CoTiSb and NiTiSn (XM x Y 1−x Z) in a wide concentration range using local-spin density functional method in the framework of tight-binding linearized muffin tin orbital method(TB-LMTO) and supercell approach. Our calculations indicate that some of these compounds are not only ferromagnetic but also half-metallic and may be useful for spintronics applications. The electronic structure of the doped systems is analyzed with the aid of a simple model where we have considered the interaction between the dopant transition metal (M) and the valence band X-Z hybrid. We have shown that the strong X-d-M-d interaction places the M-d states close to the Fermi level with the M-t 2g states lying higher in energy in comparison to the Me g states. Depending on the number of available d-electrons, ferromagnetism is realized provided the d-manifold is partially occupied. The tendencies toward ferromagnetic(FM) or antiferromagnetic(AFM) behavior are discussed within Anderson-Hasegawa models of super-exchange and double-exchange. In our calculations for Mn doped NiTiSn, the strong preference for FM over AFM ordering suggests a possible high Curie temperature for these systems.