A micromagnetic study of the reversal processes in metal-evaporated tape

The morphology of ME tape undoubtedly affects its magnetisation reversal processes. It is therefore essential that a realistic model is used when simulating the hysteresis of the film. A detailed 3D model representing the columnar structure of ME tape is developed here and the reversal processes, in an assembly of columns, are investigated numerically. The results demonstrate that reversal is affected by the strength of the exchange coupling parameter. Incoherent reversal occurs for weak coupling whereas increasing the strength brings about a high degree of co-operative reversal within columns. Strong exchange coupling and column demagnetising effects cause the moments to initially relax towards the long axes of columns. Then as the applied field is reduced the moments reverse at the column ends to form closure domains. These results indicate a subtle relationship between magnetostatic and exchange interactions occurs during reversal.