S. Kaprzyk

Crossover from semiconductor to magnetic metal in semi-Heusler phases as a function of valence electron concentration

Experimental and theoretical investigations of intermetallic semi-Heusler compounds (CoTiSn, FeTiSb, CoTiSb, NiTiSn, CoNbSn, CoVSb, NiTiSb) and their solid solutions are presented. The physical properties of these systems are found to be mostly determined by the number of valence electrons. Resistivity experiments show that compounds with 18 valence electrons are either semiconductors (CoTiSb, NiTiSn) or semi-metals (CoNbSn). The electronic structure calculations performed on 18-valence-electron systems by the KKR method show nine valence bands below the Fermi level and a gap of order 0.4-0.9 eV. A decrease or increase of the number of valence electrons in CoTiSb, NiTiSn or CoNbSn leads in either case to a metallic state and either ferromagnetic (CoTiSn, CoVSb) or paramagnetic (FeTiSb, NiTiSb) properties. The KKR results concerning 17- and 19-valence-electron systems correspond well with experimental characteristics, except in the case of CoVSb which KKR calculations predict to be a half-metallic ferromagnet, which conflicts with experimental data. Magnetization and resistivity measurements indicate that semiconductor-metal crossovers occur together with the appearance of ferromagnetism in the and series, for x near 0.4. This behaviour is discussed in the context of the KKR-CPA results.

Properties on request in semi-Heusler phases

Abstract Various transport and magnetic properties of semi-Heusler phases are described, which arise from the particular crystallographic structure and narrow band phenomena. Semiconducting-to-metal cross overs are observed by varying the electron concentration. The onset of weak itinerant ferromagnetism often arises in the metallic state. Even in NiMnSb, where the strong ferromagnetism results in a half metallic state below 80 K, the magnetism evolves from Heinsenberg-like to itinerant by increasing the temperature. Giant magnetoresistance effects are observed in the semiconducting rare earth compounds NiRSb.

Importance of relativistic effects in electronic structure and thermopower calculations forMg2Si,Mg2Ge, andMg2Sn

We present a theoretical study of the influence of relativistic effects on the electronic band structure and thermopower of Mg

Electronic structure and magnetism in CoNi Heusler compounds

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Resistivity and thermopower calculations in half-Heusler Ti1-xScxNiSn alloys from the KKR-CPA method

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High-resolution Compton scattering study of the electron momentum density in Al

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Electronic structure of a σ -FeCr compound

Si, Ge, Sn) semiconductors. The full potential Korringa-Kohn-Rostoker (KKR) method is used, and a detailed comparison between the fully relativistic and semirelativistic electronic structure features is done. We show that the spin-orbit (S-O) interaction splits the valence band at

Magnetism of Fe2P investigated by neutron experiments and band structure calculations

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Crystallographic and magnetic properties of fe2p

point in good agreement with the experimental data, and this effect strongly depends on

Search for Sc 3 X B ( X = In , Tl , Ga , Al ) perovskites superconductors and proximity of weak ferromagnetism

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