Peculiarities of the electronic transport in half-metallic Co-based Heusler alloys

• Published in: Journal of magnetism and magnetic materials 2018-08, Vol.459, p.211-214
• Main Authors: Marchenkov, V.V., Perevozchikova, Yu.A., Kourov, N.I., Irkhin, V.Yu, Eisterer, M., Gao, T.
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum; Antimony; Chromium; Curie temperature; Electric resistance; Electrical resistivity; Electromagnetism; Electron transport; Energy spectra; Germanium; Half metallic ferromagnets; Hall effect; Heusler alloys; Iron; Magnetic properties; Manganese; Nickel; Residual resistivity; Resistivity; Scattering; Silicon; Temperature dependence; Tin; Titanium; Yttrium
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2017.11.019

•Electrical, magnetic and galvanomagnetic properties of half-metallic Heusler alloys of Co2YZ.•The variation of Y strongly affects the number of current carriers and alters the electronic properties of Co2YAl.•The varying Z does not greatly change the electronic transport properties of Co2FeZ.•The temperature dependence of electroresistivity is analyzed in the frame of two-magnon scattering theory. Electrical, magnetic and galvanomagnetic properties of half-metallic Heusler alloys of Co2YZ (Y = Ti, V, Cr, Mn, Fe, Ni, and Z = Al, Si, Ga, Ge, In, Sn, Sb) were studied in the temperature range 4.2–900 K and in magnetic fields of up to 100 kOe. It was found that varying Y in Co2YZ alloys affects strongly the electric resistivity and its temperature dependence ρ(T), while this effect is not observed upon changing Z. When Y is varied, extrema (maximum or minimum) are observed in ρ(T) near the Curie temperature TC. At T ≤ TC, the ρ(T) behavior can be ascribed to a change in electronic energy spectrum near the Fermi level. The coefficients of normal and anomalous Hall effect were determined. It was shown that the latter coefficient, RS, is related to the residual resistivity ρ0 by a power law RS ∼ ρ0k/MS with MS the spontaneous magnetization. The exponent k was found to be 1.8 for Co2FeZ alloys, which is typical for asymmetric scattering mechanisms, and 2.9 for Co2YAl alloys, which indicates an additional contribution to the anomalous Hall effect. The temperature dependence of resistivity at low temperatures is analyzed and discussed in the frame of the two-magnon scattering theory.