Yun Yen

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).

In an ordinary crystal, atoms stand in neat rows like soldiers on a parade ground. Any deviation from this formation is usually considered harmful: disorder scatters waves and quickly dampens collective motions of particles.