Relative Strength of the Inter layer Dipole Fields and the Inter layer Exchange Coupling in Nanostructured Cells of Synthetic Ferrimagnets

Abstract

Both analytical and numerical calculations are carried out to examine the relative strength of the interlayer dipole fields in comparison to that of the interlayer exchange coupling in nanostructured cells of synthetic ferrimagnets as functions of their size, shape, and thickness. The relative strength in aligning the magnetizations antiparallel increases with decreasing cell size and with increasing cell thickness, in agreement with the size and thickness dependence of the magnetostatic interactions. As the cell shape changes from rectangle to ellipse, the relative strength decreases, due to the decreased density of free poles with the shape change. The relative strength of the interlayer dipole field is found to be not small, being approximately 10% of the strongest interlayer exchange coupling observed for the CoFeB/Ru/CoFeB structure. In an elliptical cell with the dimensions of 160 nm (long axis) x 80 nm (short axis) x 2 nm (thickness), for example, the strength is 0.016 erg/cm(2).