Heat-treatment behavior of the magnetic properties of epitaxial Sm0.4Y2.6Fe.3.8Ga1.2O12

Magnetization, characteristic length, uniaxial anisotropy constant, and domain wall mobility of garnet films have been measured following heat treatments in the range 900–1300 °C. Changes in the properties of films heat treated in oxygen are caused mainly by the lowering of the uniaxial anisotropy constant. The activation energy for this process is 4.1±0.2 eV, which is substantially lower than a previously reported value. Heat treatment in nitrogen leads to a lowering both of the magnetization and of the uniaxial anisotropy constant. The lowering of the magnetization is caused by a redistribution of Fe3+ and Ga3+ ions among lattice sites during the cooling part of the heat-treatment cycle. Heat treatments in oxygen are slightly more effective in lowering the uniaxial anisotropy constant than heat treatments in nitrogen.