Effect of Cu inserted layer between the IrMn and CoFeB interface on magnetic properties of CoFeB

In order to reduce the coercivity of an amorphous CoFeB layer of 10 nm thickness in a CoFeB/IrMn antiferromagnetically coupled layer, a very thin interlayer was inserted. In the present study, effects of the nonmagnetic interlayer at the interface of a ferromagnetic/antiferromagnetic on the exchange field, the coercivity and the saturation magnetization were studied. As the nonmagnetic interlayer, Cu, Ag, and Ta were used. When Cu and Ag were inserted, there was a long range bias field effect but Ta did not show any bias effect at the 0.6 nm thickness. These results are consistent with the previous articles [Gkemeijer et al. Phy. Rev. Lett. 79, 4270 (1997); J. Appl. Phys. 81, 4999 (1997)]. Thermal stability of the 0.6 nm Cu interlayer was investigated by the annealing experiment. Up to 200 °C annealing the Cu layer was stable. The dynamic magnetic reversal of the CoFeB layer with and without Cu inserted layer was observed.