Jiyuan Yang

A crystal is like a city where houses stand in neat rows. But if you slightly stretch the ground beneath the city, the houses may tilt, and the tilt can ripple as a wave from block to block. In SrTiO3 and SrMnO3 crystals, scientists have found exactly such a hidden mode: a soft wave of tilting oxygen octahedra that had gone unnoticed before.

In a perfect crystal of lead titanate, the atoms line up like soldiers on parade: all electric dipoles point the same way. To flip that formation by 180 degrees, old calculations demanded energy comparable to heating the crystal to millions of degrees.