Liang He

A hot chain of atoms lined up in a row behaves like a tiny black hole. Such a chain is a series of particles, each resembling a tiny magnet. At normal temperatures, the little magnets flip randomly, but when cooled, they align in a uniform order. Physicists have discovered that when heated, this simple system reproduces the strange properties of black holes.

Ruthenium oxide has long been regarded as a textbook altermagnet — a material where magnetic moments of neighboring atoms point in opposite directions but do not fully cancel due to the crystal's special symmetry. New measurements show that inside the crystal, there is no magnetism at all. All the magnetic action is confined to the surface.