Topologically nontrivial magnetic structures such as skyrmion lattices are well known in materials lacking lattice inversion symmetry, where antisymmetric exchange interactions are allowed. Only recently, topological multi-q magnetic textures that spontaneously break the chiral symmetry, for example, three-dimensional hedgehog lattices, were discovered in centrosymmetric compounds, where they are instead driven by frustrated interactions. Here we show that the bilayer perovskite Sr₃Fe₂O₇, previously believed to adopt a simple single-q spin-helical order, hosts two distinct types of multi-q spin textures. Its ground state represents a novel multi-q spin texture with unequally intense spin modulations at the two ordering vectors. This is followed in temperature by a new “spin meta-cholesteric” phase, in which the chiral symmetry is spontaneously broken along one of the crystal directions, but the weaker orthogonal modulation melts, giving rise to intense short-range dynamical fluctuations. Shortly before the transition to the paramagnetic state, vortex-crystal order spanned by two equivalent q vectors emerges. This renders Sr₃Fe₂O₇ an ideal material to study transitions among multiple-q spin textures in a centrosymmetric host.

拓扑非平凡的磁性结构（如斯格明子晶格）在缺乏晶格反转对称性的材料中是众所周知的，其中允许反对称交换相互作用。直到最近，在中心对称化合物中才发现了自发打破手性对称性的拓扑多 q 磁性织构，例如三维刺猬晶格，而它们是由受挫的相互作用驱动的。在这里，我们表明双层钙钛矿 Sr₃Fe₂O₇ 以前被认为采用简单的单 q 自旋螺旋顺序，具有两种不同类型的多 q 自旋纹理。它的基态代表一种新的多 q 自旋纹理，在两个有序向量处具有不等强度的自旋调制。随后在温度中出现一个新的“自旋间胆固醇”相，其中手性对称性沿晶体方向之一自发打破，但较弱的正交调制熔化，从而产生强烈的短程动力学波动。在过渡到顺磁状态之前不久，出现了由两个等效 q 向量跨越的涡旋晶体序。这使得 Sr₃Fe₂O₇ 成为研究中心对称宿主中多 q 自旋织构之间转变的理想材料。