Cooling methods using magnets to approach absolute zero
—The ultra-low temperature ”ytterbium magnetic substance” achieved with micro magnets vibrating at quantum levels—

Magnetic refrigeration is a cooling method that uses magnetic substances comprised of micro magnets, where the kinetic energy of vibrating micro magnets absorbs heat from its surroundings. Yet as temperatures decrease, the micro magnets of ordinary magnetic substances become aligned and cease moving, a fundamental flaw that prevents heat from being absorbed.

The ytterbium magnetic substance used in this research can overcome this flaw by preventing the micro magnets from becoming aligned due to quantum effects that cause vibrations, even near absolute zero. Prototypes of cooling devices made with the ytterbium magnetic substance achieved a significantly lower temperature than commercially available equipment.

With the discovery of this ytterbium magnetic substance, magnetic refrigeration could become an alternative for the current mainstream refrigeration systems using helium, which can suffer from reliable supply. Applications such as cooling for quantum computers can also be anticipated.