Barrier height imaging of magnetic films: Use for studying the initial growth of Co films and the surface structure of FePt films

► We used STM/BH imaging for studying growth of bcc Co films on Au(001). ► The BH of metastable bcc Co film was observed for the first time. ► It showed a large BH value (~ 6 eV) and the origin was also discussed. ► Aggregated Au islands and Co islands were recognized in the observed BH image. ► STM/BH studies of FePt films were also reported.