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MA: Fachverband Magnetismus

MA 15: Posters Magnetism IV

MA 15.32: Poster

Donnerstag, 30. September 2021, 13:30–16:30, P

First Principles study of spin spirals in the multiferroic BiFeO3 — •Sebastian Meyer¹, Bin Xu^2,3, Matthieu Verstraete¹, Laurent Bellaiche², and Bertrand Dupé^1,4 — ¹Nanomat/Q-mat/CESAM, University of Liége, Belgium — ²Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, USA — ³Jiangsu Key Laboratory of Thin Films, School of Physical Science and Technology, Soochow University, China — ⁴Fonds de la Recherche Scientifique (FNRS), Bruxelles, Belgium

We carry out density functional theory (DFT) calculations to explore the antiferromagnetic (AFM) spin spiral in multiferroic BiFeO3. We calculate the spin spiral energy dispersion E(q) along the high symmetry directions of the pseudo-cubic unit cell, for four different structural phases: cubic, R3c, R3m and R3c. In all cases, we find a large exchange frustration. The comparison provides detailed insight into how polarization and octahedral anti-phase tilting affect the different magnetic interactions and the magnetic ground state in BiFeO₃. For the R3c structural ground state, we find an AFM spin spiral ground state with a periodicity of ∼80 nm in good agreement with experiments and previous findings. This spin spiral is driven by a Dzyaloshinskii-Moriya (DM) interaction stemming from the Fe–Bi ferroelectric displacement. The spiral appears to be stable because the anisotropy energy in R3c BiFeO3 is too small to enforce the collinear order. For all the four phases, we discuss the magnetic ground state and identify its stabilization mechanisms [Xu, B., et al., Phys. Rev. B 103, 214423 (2021)].