arXiv subjects

O. Chumak

Publications and source records attributed to O. Chumak.

2 recordsLinked to original sources

arXiv2025

Influence of chemical ordering on magnetocrystalline anisotropy and magnetoelastic properties in Weyl magnetic semimetal Co2MnGa thin films

The magnetic anisotropy and magnetoelastic properties of the magnetic Weyl semimetal Co2MnGa were investigated in the Co2MnGa thin films with different chemical orderings. Their properties change, in line with the increase in the contents of the highly-ordered B2 and L21 phases. The most significant changes of both the magnetic anisotropy and the magnetoelastic properties were correlated with the appearance of the L21 ordered phase of Heusler alloy, which is also responsible for topological properties of these compounds. The magnetoelastic properties of L21 ordered Co2MnGa are discussed in comparison with the Co2FexMn1-xSi system with a similar degree of ordering, which has similar crystallographic structure but it is not Weyl semimetal. In particular, significant differences between the magnetoelastic properties of ordered Co2MnGa and Co2MnSi were found. In the case of L21-ordered Co2MnGa, the giant anisotropy of the magnetoelastic properties was observed.

cond-mat.mtrl-sci↗

arXiv2007

Dynamic correlations in an ordered c(2$\times$2) lattice gas

We obtain the dynamic correlation function of two-dimensional lattice gas with nearest-neighbor repulsion in ordered c(2$\times$2) phase (antiferromagnetic ordering) under the condition of low concentration of structural defects. It is shown that displacements of defects of the ordered state are responsible for the particle number fluctuations in the probe area. The corresponding set of kinetic equations is derived and solved in linear approximation on the defect concentration. Three types of strongly correlated complex jumps are considered and their contribution to fluctuations is analysed. These are jumps of excess particles, vacancies and flip-flop jumps. The kinetic approach is more general than the one based on diffusion-like equations used in our previous papers. Thus, it becomes possible to adequately describe correlations of fluctuations at small times, where our previous theory fails to give correct results. Our new analytical results for fluctuations of particle number in the probe area agree well with those obtained by Monte Carlo simulations.

cond-mat.stat-mech↗