Tathamay Basu

If you stick an ordinary piece of metal into a strong magnetic field, it warms up slightly. But some materials do the opposite: they cool down. This is called the magnetocaloric effect, and it's already being used to build future refrigerators without Freon.

In a crystal of rutile niobate, nickel atoms sit in oxygen cages — octahedra. Sometimes one atom loses an electron, and the charge hops to a neighboring atom like a baton in a relay race. But this hop is not random: it is triggered by vibrations of the entire lattice.