LLG Simulations of TbFeCo/FeNiPt CGC-Like Film

Recently, much attention has been focused on so-called “hybrid recording” such as “optically assisted magnetic recording” or “heat assisted magnetic recording”. In other words, hybrid recording is expected to be a most promising storage device beyond 1 Tera bit/inch2, ultra high density region. When the domain radius becomes very small in magneto optical recording film, the wall energy is dominant in the total energy of the domain, and then it will shrink and disappear. To write a very small domain, it is necessary to increase the domain wall coercivity to freeze the written domain. We perform three-dimensional Landau-Lifshitz-Gilbert (LLG) simulations for estimating domain shapes and wall structures in coupled granular and continuous (CGC) like films of TbFeCo film/FeNiPt grains. In the results, even when using lower Tc FeNiPt (Tc= 307 °C, Ku= 1.8×107 [erg/cm3] at room temperature) grains than FePt (Tc = 497 °C, Ku = 7.0×107 [erg/cm3] at room temperature) grains, we find a minute magnetic domain of 26 nm diameter, could be made on TbFeCo /FeNiPt bi-layer film. Moreover, the domain wall width, the obstacle in the minute magnetic domain structure of bi-layer film, is narrow. This narrowness advantageously contributes to a high density recording.