Substrate materials dependence of magnetic domain formation in CoFe nanolayer electrode patterns

Abstract The authors investigate substrate materials dependence of magnetic domain formation in CoFe nanolayer electrode patterns. Without any application of magnetic fields, B , we observe the marked reflux, double reflux, and single magnetic domains in the case of samples with relatively thick 4-nm-MgO interlayers and 1-μm-thick amorphous SiO 2 layers under CoFe. The CoFe nanolayer electrode patterns with thinner 1-nm-MgO interlayers form large numbers of (or multiple) small magnetic domains. In addition, single magnetic domains are formed in the cases of CoFe/MgO (1 and 4 nm in thickness) nanolayer electrode patterns with the aspect ratio of 4 after applying B , whereas other patterns tend to have multiple or reflux magnetic domains. Multiple magnetic domains are markedly more formed in the CoFe nanolayer electrode patterns with thinner 1-nm-MgO interlayers than thicker 4-nm-MgO ones. These results suggest that surface-roughness of layers under CoFe plays an important role for the magnetic domain formation in CoFe.