Temperature-dependent resistivity and anomalous Hall effect in NiMnSb from first principles

Abstract

We present implementation of the alloy analogy model within fully relativistic density functional theory with the coherent potential approximation for a treatment of nonzero temperatures. We calculate contributions of phonons and magnetic and chemical disorder to the temperature dependent resistivity, anomalous Hall conductivity (AHC), and spin-resolved conductivity in ferromagnetic half-Heusler NiMnSb. Our electrical transport calculations with combined scattering effects agree well with experimental literature for Ni-rich NiMnSb with 1 to 2 % Ni-impurities on Mn-sublattice. The calculated AHC is dominated by the Fermi surface term in the Kubo-Bastin formula. Moreover, the AHC as a function of longitudinal conductivity consists of two linear parts in the Ni-rich alloy, while it is non-monotonic for Mn impurities. We obtain the spin polarization of the electrical current P > 90% at room temperature and we show that P may be tuned by a chemical composition. The presented results demonstrate the applicability of efficient first principle scheme to calculate temperature dependence of linear transport coefficient in multisublattice bulk magnetic alloys.

Electron Transport in High-Entropy Alloys: Al _xCrFeCoNi as a Case Study

“…Since we cannot determine the magnitude of the local relaxations quantitatively, we have performed only a preliminary study in order to get rough estimation of their effect on the resistivity by employing the alloy analogy model in the CPA. 24,29 As a typical mean value of the atomic displacement, we took ∆u = 0.05 Å for fcc alloys (obtained for the fcc Cantor alloy) 11 and a slightly higher value ∆u = 0.075 Å for bcc alloys (because of the more open bcc geometry). The resulting increase of the residual resistivity of Al x CrFeCoNi was small in both structures, being about 2.8 % for x = 0.25 in the fcc case and about 1.4 % for x = 1.25 in the bcc case.…”

Antiferromagnetic CuMnAs: Ab initio description of finite temperature magnetism and resistivity

“…To describe spin fluctuations, we employ a collinear uncompensated DLM (uDLM) approach and a tilting model, which were used for FM NiMnSb [11] and [12]. Moreover, we introduce their combination, later called "tilting uDLM".…”

“…Fig. [12]; however, missing effects of impurities and phonons may be nontrivial, see the next subsection, and because of absence of experimental data, this cannot be studied in greater detail for CuMnAs. If tetragonal bulk samples of CuMnAs are available, we suggest measuring the out-of-plane resistivity at higher temperatures in order to determine, which model of the spin fluctuations is the most realistic.…”

“…The alloy analogy model (AAM) has recently been implemented [8,9,10] within the tight-binding linear muffin-tin orbital (TB-LMTO) method with the coherent potential approximation (CPA) and used to describe ferromagnetic (FM) half-Heusler NiMnSb at finite temperatures [11,12]. Previous studies of other groups employing the AAM are based on i) the CPA and the Korringa-Kohn-Rostoker (KKR) method with the Kubo-Bastin equation [13,14,15] and on ii) supercells with the TB-LMTO method and the Landauer-Büttiker formula [16,17], but they focus on transition metals.…”

“…2 (e)-(h), DOS for maximal spin disorderwithin the tilting uDLM model (c θ = 0.10) is shown by dashed lines. Sharp peaks are smeared in presence of spin fluctuations but, unlike to NiMnSb[12],…”