STRUCTURAL TRANSFORMATIONS OF FCC IRON FILMS ON CU(100)

Structural transformations of fcc iron films deposited on Cu(100) at r oom temperature have been investigated by scanning tunneling microscop y (STM) and low energy electron diffraction (LEED). Iron films of appr oximately 10 ML (monolayers) are metastable upon further iron depositi on, mild sputtering or cooling to 170 K The structural transition is c onnected with dislocation formation. Using electron diffraction, strea ks running in the [011]-direction are observed. These streaks are most intense at positions close to those of a (3 x 1) structure. STM studi es show that the transformation is connected with the appearance of st ripes running in the [011]-direction on the surface. These stripes are often found in the vicinity of dislocation lines. They serve as nucle ation centers for the growth of bcc iron with a (110) orientation on t he Cu(100) surface.