Anisotropy Constant And Exchange Coupling Strength Of Perpendicularly Magnetized Cofeb/Pd Multilayers And Exchange Springs

A model describing the ferromagnetic resonance of multilayer structures is used to characterize the interface anisotropy constant and interlayer exchange coupling strength associated to individual components of [CoFeB/Pd](n) multilayers with perpendicular magnetic anisotropy and [CoFeB/Pd](5)/(CoFeB or Co) exchange spring structures by comparing with ferromagnetic resonance behavior measurements. We find that the effective perpendicular anisotropy increases with the number of repetitions of the multilayer, which we could explain only after accounting for a different anisotropy at the bottom repetition of the multilayer with perpendicular anisotropy. Similarly, the characterization of the exchange coupling in our structures was only possible after accounting for individual components, thus portraying the importance of using a multilayer model to properly describe the magnetic behavior and properties of a multilayer structure. We find that the perpendicular anisotropy constant in amorphous Pd/CoFeB/Pd structures increases slightly from 0.295 to 0.315 mJ/m(2) when increasing the thickness of the CoFeB from 3 to 4 angstrom. Furthermore, we find that the exchange coupling in CoFeB/Pd(10 A degrees)/CoFeB structures decreases from 4.899 to 3.268 mJ/m(2) when increasing the thickness of the CoFeB from 3 to 4 angstrom. Finally, we find that the magnitude of the anisotropy at Co/Pd interfaces is 65% larger than at CoFeB/Pd interfaces, and the exchange coupling at CoFeB/Pd/Co interfaces decreases approximately 30% when compared to a CoFeB/Pd/CoFeB structure.