2nd Users' Conference of IT4Innovations

Alloy analogy model: Fully relativistic electrical transport with phonons, magnons, and chemical disorder

Nov 7, 2018, 11:45 AM

15m

atrium (IT4Innovations)

User's talk Users' talks Users Talks I.: 6 contributions each 15 mins

Speaker

Mr David Wagenknecht (Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University)

Description

We will present implementation and applicability of the alloy analogy model (AAM) within fully relativistic *ab initio* computational framework with the coherent potential approximation (CPA). Reliable treatment of temperature-induced disorder in solids is still a challenging task, especially because of numerical expenses or realisticity of approaches. Our tight-binding linear muffin-tin orbital method numerical (TB-LMTO) numerical codes with the CPA-AAM represent a perfect tool for a study of combined contribution of atomic displacements (phonons), spin fluctuations (magnons) and chemical impurities [1,2]. We will show calculations of electronic structure (Bloch spectral function) and transport properties (electrical resistivity, anomalous Hall conductivity) with primary focus on describing spintronic devices influenced by realist room-temperature disorder. Perfect agreement with experimental data is obtained not only for simple metals and binary alloys but also for complex systems like half-Heusler NiMnSb. Discussion of numerical efficiency of our approach will be included and we will also show prediction of experimentally important but hardly-accessible quantities like spin-polarization of electrical current. Our investigation of finite-temperature material properties is also extremely useful for an identification of chemical impurities in specific samples and the developed methods may be used to study of wide range of metalic materials and to efficiently deal with a combination of chemical, magnetic, and temperature-induced disorder.

Summary

The alloy analogy model implemented within tight-binding linear muffin-tin orbital method with the coherent potential approximation will be presented with a focus on combined effect of phonons, magnons and chemical impurities in magnetic solids.
We will show fully relativistic ab initio calculations of electrical transport properties treated in a basis of noncolinear magnetism in order to realistically describe temperature-induced disorder in materials useful for spintronic devices, e.g., half-metalic NiMnSb.
Our methods may be used to identify chemical disorder in real samples, calculated results perfectly agree with experimental data, and we will also discuss nontrivial quantities like spin polarization of electrical currents.

References

[1] D. Wagenknecht et al. IEEE Trans. Magn. 53, 11, 1700205 (2017)

[2] D. Wagenknecht et al. Proc. SPIE 10357, Spintronics X; 103572W (2017)