Magnetic domain structure of Fe sub(14)Nd sub(2)B single crystals between 135 and 4 K and the low-temperature magnetization reversal process in Fe-Nd-B permanent magnets

The magnetic domain structure of Fe sub(14)Nd sub(2)B single crystals has been studied from room temperature down to 4.2 K by means of the magneto-optical Kerr effect. It was found that the coercivity of different domain walls essentially depends on their type and orientation. The general expressions for the domain wall energy density gamma have been performed for Fe sub(14)Nd sub(2)B compounds in the low-temperature region. The role of the new domain wall types in the low-temperature magnetization reversal process in Fe-Nd-B permanent magnets is discussed.