Large stable magnetic domains

Abstract

Large, thin-film single domain areas have been observed, in the absence of a bias field, in garnets with magnetization perpendicular to the film plane.1,2 The domain stability in the work by Krumme1 was attributed to a combination of low saturation magnetization and a low Curie temperature. Uchishiba2 relates the stability in his double layer system to appropriate anisotropy fields in one layer compared to the magnetization in the other layer. A more complete model for large domain stability in a bias field free environment is given in this work. Three distinct stability regimes are predicted by the model and all have been observed experimentally. Areas 3.5-cm in diameter have been made into stable single domains. This was achieved in a material showing a zero bias strip width of 4.5 μm. The single domain diameter was, therefore, 7500 times the equilibrium energy domain width. The technique developed and the model have led to a new means for observing magnetic defects. More importantly, it also offers a means for measuring the strength of the defects. Possible applications of the model are also discussed.