A. Martinelli

A kitchen sponge squeezed in your fist springs back. But if you squeeze it slowly while letting it dry, it stays flattened. That's roughly what scientists did with tiny gel beads: they let them dry while compressing them, and watched what happened inside. A gel is made of tiny particles that stick together into an open, lacy network, like cereal flakes in a bowl of milk.

The strontium ferrite crystal is like a multi-story building where each floor hosts iron atoms. Some floors "look" up, others down, and their magnetic fields partially cancel each other out. But if some of the residents are replaced with aluminum, which doesn't play the magnetic game, the balance of forces shifts.