A layered magnet is like a stack of paper: each sheet is a thin crystalline layer, and foreign atoms can be inserted between them like bookmarks. In the material Co₁₋ₓFeₓNb₃S₆, some cobalt atoms are replaced by iron, and this substitution acts like changing the paper type in the stack. The sheets start vibrating differently, and the whole stack responds differently to a magnetic field.

With a small iron addition (x = 0.1), two magnetization jumps appear in a magnetic field, and the electrical resistance traces a whimsical loop resembling butterfly wings. A weak 'topological' contribution to resistance also emerges, as if electrons flying through the material sense a twisted magnetic pattern. But when the iron fraction is increased to x = 0.3, the loop becomes simple, the butterfly disappears, and the topological contribution vanishes. The magnetic order becomes stiffer: the transition temperature to the ordered state rises from 20–24 K to 32 K.

Light scattering experiments (Raman spectroscopy) showed that adding iron shifts one lattice vibration frequency upward, and near the magnetic transition for x = 0.1, weak anomalies are visible — a sign that atomic vibrations and magnetic order are slightly coupled. Such coupling could become a tool for controlling magnetic properties through mechanical means.

Similar layered antiferromagnets are considered a basis for spintronics — electronics where information is carried not by electron charge but by spin (the intrinsic magnetic moment). If the magnetic pattern can be controlled via composition or strain, energy-efficient memory and logic devices could emerge.