In a ballroom where couples were dancing, the music changed, and the pairs lined up in rows suddenly spun into whirlpools. That is how the magnetic crystal Fe3Ge rearranges its internal pattern once the temperature climbs above 375 kelvins, which is about a hundred degrees of heat. Below that threshold, the magnetic arrows in the crystal lie flat, like couples waltzing in circles. Above it, they stand upright, and tiny vortices of magnetization, which physicists call skyrmions, are born in the material.

The Fe3Ge crystal is built from iron and germanium atoms, and its lattice looks like a basket woven from triangles. This pattern is called a kagome lattice, after a Japanese weaving style. In this pattern, electrons move in a peculiar way, as if they had no mass, and because of that the material carries current across an applied voltage even without an external magnet. This effect, the anomalous Hall effect, reaches 380 siemens per centimeter to the power of minus one at room temperature, comparable to the best materials of this class.

To see the vortices, the researchers cut a plate a hundred nanometers thick from the crystal and shone a beam of electrons through it. The magnetic vortices deflected the beam, and a pattern of bright and dark spots appeared on the image. It turned out that the vortices swirl both left and right in equal proportions. This symmetry suggests that the vortices are held together not by some external field but by the material's own magnetic forces, like couples who spin because they themselves want to dance.

Why does this matter? A vortex can be nudged with a tiny current, and it will not fall apart, which means its position can serve as a zero or a one in memory. Conventional hard drives store bits in magnetic domains, but those require more energy to switch and take up more space. Skyrmions in Fe3Ge promise memory that works in heat where ordinary electronics already give up. True, the vortices do not yet reach room temperature: they are born only above 375 kelvins, when the magnetic arrows stand upright. The next step is to find a substitute for some of the iron or germanium atoms so that the dance starts at 300 kelvins.

But even now this crystal is a rare venue where two different dances meet. One is vortices in space, visible under a microscope. The other is vortices in the world of electronic states, which reveal themselves through the anomalous Hall effect. Previously these two phenomena were studied separately, in different materials. Fe3Ge shows that they can whirl in the same ballroom, to the same music, and this opens a path to devices where spin textures are controlled by electric fields through topological electronic states.

The dance floor in the Fe3Ge crystal does not empty even at 650 kelvins, when the vortices finally dissolve into the general motion. Until that threshold the music does not stop, and the couples keep the rhythm from a hundred degrees of heat to red heat. Perhaps it is in materials like these that memory will be born that needs no refrigerator.