Transport properties of doped permalloy via ab initio calculations: Effect of host disorder

Abstract

Transport properties of permalloy doped with V, Co, Pt, and Au are explored via ab-initio calculations. The Kubo-Bastin formula is evaluated within the fully relativistic Korringa-Kohn-Rostoker Green function formalism. Finite temperature effects are treated by means of the alloy analogy model. It is shown that the fact that the host is disordered and not crystalline has a profound effect on how the conductivities characterizing the anomalous Hall effect and the spin Hall effect depend on the dopant concentration. Several relationships between quantities characterizing charge and spin transport are highlighted. The decrease of the longitudinal charge conductivity with increasing doping depends on the dopant type, following the sequence Co-Au-Pt-V. The dependence of the anomalous Hall and spin Hall conductivities on the dopant concentration is found to be non-monotonic. Introducing a finite temperature changes the overall trends significantly. The theoretical results are compared with available experimental data.

Spin-orbit-coupling induced lateral spin transport from first principles

“…Using ab initio calculations, we have shown in chapter 3 that a large spin Hall current can be generated in the bulk of Py and Ni in agreement with other calculations [38,137,157]. Recent experiments using non-local measurements [36,39] reported a large spin Hall effect in Py.…”

“…Miao et al realized the IAHE (but termed it the ISHE) by using a thermal gradient in the ferromagnetic insulator YIG (Yttrium Iron Garnet) to inject a spin current into the ferromagnetic alloy permalloy (Py=Ni 80 Fe 20 ) and produced a transverse charge current with an efficiency comparable to, albeit smaller than, that of Pt [122]. Subsequent experiments [36,39,[123][124][125][126][127][128][129][130][131][132][133][134][135] and theoretical investigations [38,42,121,136,137] confirm their observation that for Py and other 3d ferromagnetic materials spin Hall effects are comparable in magnitude to those observed in 5d materials leaving one to wonder if the absolute value of the SOC parameter ξ alone determines the size of Θ sH . The hopping between orbitals on neighbouring atoms that is measured by the bandwidth W reduces the effective spin orbit splitting by mixing the split states [138,139].…”

Effect of atomic anti-site disorder on the AMR in FeCo alloys

“…The vertex correction is crucial for discussing the scattering of impurities in electronic transport [31,32], which corresponds to the scattering-in term in the Boltzmann equation [33,34]. However, the effect of the vertex correction is much weaker if the states at the Fermi energy have d properties primarily [35,36,37].…”

“…The enhancement of anti-site disorder also dramatically raises the value of the constant term A. The cos 4α term's coefficient D, which characterizes the single crystal anisotropic magnetoresistance, reduces remarkably with the degree of disorder, as shown in FIG.3 (b).The vertex correction is crucial for discussing the scattering of impurities in electronic transport[31,32], which corresponds to the scattering-in term in the Boltzmann equation[33,34]. However, the effect of the vertex correction is much weaker if the states at the Fermi energy have d properties primarily[35,36,37].…”

Temperature-induced changes in the magnetism of Laves phase rare-earth--iron intermetallics by ab~initio calculations

“…We employ ab initio calculations to investigate how the spin magnetic moment µ spin , the orbital magnetic moment µ orb , and especially the ratio µ orb /µ spin vary for RFe 2 if the temperature increases from zero to the Curie temperature T C . To perform thermal averaging, we employ the alloy analogy model, which proved to be useful in studying the temperature-dependence of various magnetismrelated properties in the past [17,18]. We will show below that the µ orb /µ spin ratio for Fe in RFe 2 increases with increasing temperature by as much as 70 %.…”