Micromagnetic description of twisted spin spirals in the B20 chiral magnet FeGe from first principles

Using the model of classical Heisenberg exchange and Dzyaloshinskii-Moriya (DM) interaction, we show that ground state B20 FeGe chiral magnet is a superposition twisted helical spin-density waves formed by different sublattices crystal. Such propagate in same direction but with phases directions rotation axes. We derive an advanced micromagnetic expression describing DM interaction for such magnetic structures. In particular, order gives rise to new contributions energies interactions. By employing first-principles calculations based on density functional theory using our magnitude spin-spiral twist as global spiraling. While energy difference between spirals ferromagnetic good agreement experimental results, spin without it smaller factor 3. addition, verify results spin-dynamics simulations. This calls experiments exploring properties magnets.