Explanation

Anisotropy of ferromagnetic and ferrimagnetic materials when single crystals are magnetize in different directions. Generally, the crystal directions that are easiest to magnetize and hardest to magnetize are called easy magnetize direction (easy axis) and difficult magnetize direction (difficult axis) respectively. For example, the easy magnetize direction of iron is [100], the difficult magnetize direction is [111], the easy magnetize direction of nickel is 111, and the difficult magnetize direction is 100; They all have multiple easy magnetize directions. Cobalt in hexagonal system has only one easy magnetize direction, namely [000] direction. The magnetocrystalline anisotropy reflects that the free energy of magnetic domain (spontaneous magnetization vector) is different when they are arranged along different crystal directions. The commonly used expression for magnetic crystal anisotropy is EK. The magnetocrystalline anisotropy constants of different materials are different, which mainly depend on the chemical composition and crystal structure of materials, as well as the structural state. The reason for magnetocrystalline anisotropy is the effect of crystal field on the coupling of electron fl spin orbit, which causes the anisotropic interaction between electron spins, called quasi dipole moment interaction, or anisotropic exchange interaction. magnetocrystalline anisotropy has a great influence on the magnetize process of multi crystalline materials, and materials with high permeability often require their anisotropy constants to be as small as possible.

Classification