V. Balédent

The Fe₃Sn₂ crystal looks like a patterned lattice where iron atoms sit at the corners of hexagons. Under normal conditions, their magnetic arrows are aligned neatly, like soldiers in a row. But squeeze the crystal, and the alignment breaks. Under a pressure of about 20 gigapascals (imagine twenty elephants standing on your thumbnail), the lattice slightly rearranges.

A Prussian blue analogue crystal is like a frame house with empty rooms: metal ions sit at the corners, and cyanide bridges stretch between them. Water molecules can live inside these rooms, and how many there are determines the behavior of the whole house. In this study, the researchers filled the rooms differently for several compounds and watched how the magnetic order changed.