The magnetic refrigerator of the future won't hum with a compressor. Instead, it will cool your groceries by exploiting a special material that heats up in a magnetic field and cools down when the field is removed. This cycle resembles the compression and expansion of gas in a conventional fridge, but here a magnet does the work of a piston.
To figure out how well a material suits such a refrigerator, you need to measure three things: how much heat it releases, how strongly it cools, and how its heat capacity changes. Until now, each measurement required its own device, sometimes even a homemade setup. The authors of the new study showed that all of this can be done on a single commercial instrument — the VersaLab, which is already available in many labs.
The scientists tested the method on Gd5Si2Ge2, a material that changes its structure at a certain temperature. For a magnetic field change from 0 to 1 tesla (roughly the field of an MRI magnet), they achieved a cooling of 4.47 degrees. This differs by only one percent from the direct temperature measurement on the same material.
Now any researcher can quickly and accurately test new magnetic cooling materials without assembling complex setups. This will speed up the development of quiet, efficient refrigerators that don't rely on harmful gases.
Magnetic cooling is already used in labs to reach temperatures below 1 kelvin — colder than outer space.
In Andy Weir's novel The Martian, the protagonist uses a radioisotope heater, but magnetic cooling could aid life-support systems on Mars, where reliability without moving parts is crucial.