Speaker
Description
For a purpose of novel electronic and spintronic applications, it is desired to describe realistic behavior of magnetic materials from first principles. Ab inito approaches can save a lot of experimental expenses; however, it is extremely complicated to compute material properties influenced by real-life phenomena. For a design of new devices, treatment of chemical impurities and temperature-induced disorder (phonons and magnons) is essential because, e.g., computers should be reliable not only at temperature of $T=0$ K.
We will present implementation of the alloy analogy model (AAM) within the tight-binding linear muffin tin orbital method and the coherent potential approximation, which was successfully used to described electrical transport of transition metals and random alloys [1, 2]. Within this formalism, effects of finite temperature and their combination with impurities can be treated. The technique is both robust and numerical effective; therefore, it can be employed also for complex multi-sublattice materials.
Especially recent comprehensive study of half-Heusler NiMnSb [3, 4] will be shown with a focus on spintronic applications and experimentally hardly-accessible quantities such as spin polarization of the electrical current $P$. For example, influences of atomic vibrations, spin fluctuations, and alloying on electrical transport and the polarization $P$ can be separated in our calculations in order to show that the spin disorder has the highest influence on $P$, which is supposed to be above $90 \%$ at ambient conditions (room temperature, realistic impurities) anyway. Last but not least, perfect agreement with experimental literature will be presented and aspects of the AAM for the high-performance computing discussed.
[1] D. Wagenknecht et al. IEEE 53, 11, 1700205, (2017)
[2] D. Wagenknecht et al. Proc. SPIE 10357, Spintronics X, 103572W (2017)
[3] D. Wagenknecht et al. JMMM 474, 517 (2019)
[4] D. Wagenknecht et al. PRB 99, 174433 (2019)
