Nucleation, pinning, and coercivity in magnetic nanosystems: An analytical micromagnetic approach

Nucleation and pinning fields have been derived for an exchange-coupled hard/soft/hard magnetic nanosystem within an analytical micromagnetic approach. For the first time, the analytical formulas can be directly compared with the numerical and experimental coercivity to differentiate the coercivity mechanisms quantitatively. In addition, our analytical results demonstrate that the nucleation field decreases with the soft layer thickness Ls parabolically, rather than reaching a plateau at small Ls as claimed by other reports. The coercivity paradox and the attainable maximum energy product are reexamined based on our results.