  Noncollinear magnetic moments in antiferromagnets (AFM) lead to a complex
behavior of electrical transport, even to a decreasing resistivity due to an
increasing temperature. Proper treatment of such phenomena is required for
understanding AFM systems at finite temperatures; however first-principles
description of these effects is complicated. With ab initio techniques, we
investigate three models of spin fluctuations (magnons) influencing the
transport in AFM CuMnAs; the models are numerically feasible and easily
implementable to other studies. We numerically justified a fully relativistic
collinear disordered local moment approach and we present its uncompensated
generalization. A saturation or a decrease of resistivity caused by magnons,
phonons, and their combination (above approx. 400 K) was observed and explained
by changes in electronic structure. Within the coherent potential
approximation, our finite-temperature approaches may be applied also to systems
with impurities, which are found to have a large impact not only on residual
resistivity, but also on canting of magnetic moments from the AFM to the
ferromagnetic (FM) state.
