A crystal is like a hall with two types of seats: some have four neighbors, others have six. Usually, in extreme cold, everything freezes in place, like spectators in a dark theater. But in this crystal, at minus 268 degrees Celsius, iron and magnesium atoms began to swap: iron moved to seats with six neighbors, and magnesium to seats with four. The temperature is so low that thermal motion is almost absent, yet the relocation still occurs.

The cause turned out to be magnetism. When the crystal cools, magnetic order emerges within it, acting like a conductor setting a new score. Atoms follow this score and change places. Scientists verified this by compressing the crystal under pressure: then the atoms swapped in the opposite direction. So it is not about contraction from cold, but specifically about magnetic order. Previously, it was thought that at such temperatures atoms in a solid are completely immobile, but now it is clear that magnetic forces can move them. For now, this is pure knowledge, but it will help understand how materials behave in space and in superconducting devices.