Spin excitations of a multiple-q chiral spin texture on a centrosymmetric lattice

Magnetic materials with helical spin arrangements are known as helimagnets. Most of them have a chiral crystal structure, which defines the chirality of the magnetic texture. In some rare cases, however, chiral spin textures can occur in centrosymmetric lattices, meaning that the chiral symmetry is spontaneously broken by the magnetic order. The two related perovskites SrFeO₃ and Sr₃Fe₂O₇ are examples of such materials. They form complex multi-q magnetic chiral textures at low temperatures and exhibit a cascade of phase transitions, driven by temperature or magnetic field, resulting in a rich magnetic phase diagram with exotic phases. The magnetic excitations in these two compounds have been studied by neutron scattering, which revealed not only coherent spin-wave excitations but also diffuse quasielastic magnetic scattering that sets in at elevated temperatures. We suggest that this anomalous contribution originates from chiral domain walls and should be a generic feature of all centrosymmetric helimagnets.

Original articles:

• N. D. Andriushin, J. Grumbach, A. A. Kulbakov, Y. V. Tymoshenko, Y. A. Onykiienko, R. Firouzmandi, E. Cheng, S. Granovsky, Y. Skourski, J. Ollivier, H. C. Walker, V. Kocsis, B. Buchner, B. Keimer, M. Doerr, D. S. Inosov, D. C. Peets; Anomalous quasielastic scattering contribution in the centrosymmetric multi-q helimagnet SrFeO₃. Phys. Rev. X 15, 011038 (2025).
• N. D. Andriushin, J. Muller, N. S. Pavlovskii, J. Grumbach, S. Granovsky, Y. V. Tymoshenko, O. Zaharko, A. Ivanov, J. Ollivier, M. Doerr, B. Keimer, M. Mostovoy, D. S. Inosov, D. C. Peets; Reentrant multiple-q magnetic order and a "spin meta-cholesteric" phase in Sr₃Fe₂O₇. npj Quantum Materials 9, 84 (2024).