A laser flash strikes a copper oxide crystal, and magnetic excitation waves, magnons, ripple outward like ripples on water. For the first time, scientists traced their path from birth to disappearance with femtosecond precision (millionths of a billionth of a second).
First, light knocks out electrons, and the atomic spins (their internal 'little magnets') instantly lose order. A cloud of magnons with a wide range of momenta is born, like a crowd suddenly chattering in every language at once. Within picoseconds (trillionths of a second), this cloud settles into relative order: magnons exchange energy among themselves but do not yet give it up to the crystal lattice.
This scenario is a universal key to ultrafast magnetism control. Knowing exactly where energy gets stuck, one can design materials with desired response times for future data storage and processing devices.
A magnon is not a particle but a coordinated oscillation of many atomic spins, similar to a wave traveling through a stadium crowd.
In Peter Watts's novel 'Blindsight,' alien beings use quantum effects for ultrafast information processing — somewhat akin to how magnons carry energy without moving matter.