Thermally assisted magnetization reversal of sub-100 nm dots with perpendicular anisotropy has been investigated using a micromagnetic Langevin model. The performance of the two different reversal modes of (i) a reduced barrier writing scheme and (ii) a Curie point writing scheme are compared. For the reduced barrier writing scheme, the switching field Hswt decreases with an increase in writing temperature but is still larger than that of the Curie point writing scheme. For the Curie point writing scheme, the required threshold field Hth, evaluated from 50 simulation results, saturates at a value, which is not simply related to the energy barrier height. The value of Hth increases with a decrease in cooling time owing to the dynamic aspects of the magnetic ordering process. Dependence of Hth on material parameters and dot sizes has been systematically studied.
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