2025/06/20 by Lee, Seungho, Kim, Se Kwon
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Nonlinear Photonic Systems #Physics of Superconductivity and Magnetism #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2506.16818
openalex publication_date 2025/06/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We derive an effective field theory for a noncollinear altermagnet and magnons on top of the noncollinear ground state from an altermagnetic Heisenberg model. We obtain the ground-state phase diagram, revealing a noncollinear phase and four distinct collinear phases. The ground state of the noncollinear phase fully breaks the spin rotational symmetry, while the ground state of the collinear phases possesses unbroken SO(2) symmetry. The resulting effective field theory for the noncollinear phase is an SO(3) sigma model in which the magnonic excitation has three independent degrees of freedom and exhibits the d-wave-like anisotropic linear dispersion. We also discuss possible topological solitons, including ℤ2 vortices.