paper

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

arXiv:1712.01584 · doi:10.1016/j.jmmm.2017.11.019

Abstract

Electrical, magnetic and galvanomagnetic properties of half-metallic Heusler alloys of Co $_{2}$ YZ (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 affects strongly the electric resistivity and its temperature dependence $I ¨ (T)$ , while this effect is not observed upon changing Z. When Y is varied, extrema (maximum or minimum) are observed in $I ¨ (T)$ near the Curie temperature $T_{C}$ . At $T < T_{C}$ , the $I ¨ (T)$ behavior can be ascribed to a change in electronic energy spectrum near the Fermi level. The coefficients of the normal and anomalous Hall effect were determined. It was shown that the latter coefficient, $R_{S}$ , is related to the residual resistivity $I ¨ _{0}$ by a power law $R_{S} \sim I ¨ _{0}^{k} / M_{S}$ with $M_{S}$ the spontaneous magnetization. The exponent $k$ was found to be 1.8 for Co $_{2}$ FeZ alloys, which is typical for asymmetric scattering mechanisms, and 2.9 for Co $_{2}$ YAl 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 framework of the two-magnon scattering theory.

Invited Report on the Moscow International Symposium on Magnetism MISM-2017, pdf only, 6 pages, J. Magn. Magn. Mater., in press