Magnetic domains in mono and polycrystals (The)

The crystal is formed by small volume elements magnetized to saturation as a result of interactions between neighbouring spins that tend to align in parallel. These volume elements are called magnetic domains, the adjacent domains being separated by transition zones called block walls. The film aims to study the dynamics of these walls, i.e. their movements when the crystal is subjected to a magnetic field.
The experimental study itself uses a metallographic microscope. The sample, covered with a colloidal magnetite suspension whose particles are very fine (1000 Ao), is then filmed by microcinematography.
Three types of materials are studied: metallic single crystals (cobalt, iron and nickel), ferrite single crystals (magnetoplumbite and magnetobaryte) and polycrystals (non-oriented and grain-oriented transformer sheet, nickel ferrite obtained by sintering).