Barium ferrite, abbreviated BaFe, BaM, is the chemical compound with the formula BaFe12O19. This and related ferrite materials are components in magnetic stripe cards and loudspeaker magnets. BaFe is described as Ba2+(Fe3+)12(O2−)19. The Fe3+ centers are ferrimagnetically coupled, and one unit cell of BaM has a net magnetic moment of 40μB .This area of technology is usually considered to be an application of the related fields of materials science and solid state chemistry.