Superconductors are substances that have no electrical resistance.Many people may have seen it in science textbooks, but it is used in places that are surprisingly familiar.For example, the operation of MRI used in hospital examinations requires strong magnetism, so electromagnets using superconductors are used.However, in order to reduce the electrical resistance to zero, it is necessary to cool it to an extremely low temperature of -200 ° C or less with a rare and expensive liquid helium, which is costly.Under these circumstances, the development of superconducting magnets that can operate even at higher temperatures is desired.

　A candidate for this is a superconductor made from iron.Since it reaches a superconducting state even at a relatively high temperature, it is expected that superconducting magnets can be realized at low cost.However, until now, the technology for making magnets from iron-based superconductors has not been established.Associate Professor Yamamoto and his colleagues focused on compounds made from iron, including barium, potassium, and arsenic.It is a compound known to be in a superconducting state even at relatively high temperatures.By baking the fine crystals of this compound to form a mass called polycrystal, it became a powerful superconducting magnet that can operate even in a small refrigerator.Previous polycrystals had the weakness of being easily cracked from the joints of grains, but this magnet has uniform grains and high strength.

　With the establishment of technology for making magnets from iron-based superconductors, it will be possible to significantly reduce the cost of MRI examinations in the future.In addition, magnets made from polycrystals have the disadvantage of being broken by strong magnetic force, but demonstrating a method to overcome this may open up new paths for magnets made from other materials.