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

Abstract

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

arXiv comment12 pages, 7 figures

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Cited by in corpus (5)

• Magnetic interactions and possible structural distortion in kagome FeGe from first-principles study and symmetry analysis
• Experimental determination of the spin Hamiltonian of the cubic chiral magnet MnSi
• Spatially modulated, orbital selective ferromagnetism in La${}_5$Co${}_2$Ge${}_3$
• Origin of the suppression of magnetic order in MnSi under hydrostatic pressure
• The influence of antiferromagnetic spin cantings on the magnetic helix pitch in cubic helimagnets