Barium ferrite
![Barium Ferrite was used in tape drives and floppy disks, among other things.](/Images/godic/202412/23/Dds_tape_drive_011102.jpg")
Barium ferrite, abbreviated BaFe, BaM, is the chemical compound with the formula BaFe2O4. This and related ferrite materials are components in magnetic stripe cards and loudspeaker magnets. BaFe is described as Ba(Fe)2(O)4. The Fe centers are ferromagnetically coupled. This area of technology is usually considered to be an application of the related fields of materials science and solid state chemistry.