Magnetic refrigeration uses the magnetocaloric effect of magnetic refrigeration materials to discharge energy to the outside world during isothermal magnetization and absorb heat from the outside during demagnetization, so as to achieve the purpose of refrigeration. The refrigerant in magnetic refrigeration technology is a solid magnetic material. When the magnetic material is magnetized, the magnetic moment order increases, the magnetic entropy decreases, the temperature rises and releases heat to the outside world; During demagnetization, the magnetic moment order of the magnetic material decreases, the magnetic entropy increases and the temperature decreases,

Absorb heat from the outside.

According to the temperature range of application, magnetic refrigeration materials can be divided into three temperature regions: extremely low temperature, low temperature and high temperature. GGG single crystal can be applied to the extremely low temperature region below 20K and successfully applied to the refrigeration before he Ⅱ flow helium nitrogen liquefaction. Recently, the research on GGG refrigeration cooperated by Crestron and the Institute of physical and chemical technology of the Chinese Academy of Sciences has achieved good results: at present, the minimum temperature can reach 540mk.

Compared with traditional refrigeration technology, magnetic refrigeration technology has the advantages of high efficiency, energy saving, no pollution, stable and reliable operation. It will have broad application prospects in daily life, industrial production, agriculture, military, aerospace and other fields in the future.