STRUCTURAL TRANSFORMATIONS OF FCC IRON FILMS ON CU(100)

Structural transformations of fcc iron films deposited on Cu(100) at room temperature have been investigated by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). Iron films of approximately 10 ML (monolayers) are metastable upon further iron deposition, mild sputtering or cooling to 170 K The structural transition is connected with dislocation formation. Using electron diffraction, streaks running in the [011]-direction are observed. These streaks are most intense at positions close to those of a (3 x 1) structure. STM studies show that the transformation is connected with the appearance of stripes running in the [011]-direction on the surface. These stripes are often found in the vicinity of dislocation lines. They serve as nucleation centers for the growth of bcc iron with a (110) orientation on the Cu(100) surface.