OBSERVATION OF AN ORDERED NEW COMPOUND CO1-XRUX PREPARED BY MBE ON A RU BUFFER LAYER

Co1-xRux (x approximate to 21 and 25 at%) thin layers (35 nm) have bee n grown by molecular beam epitaxy on a Ru [00.2] buffer layer on mica substrates at different temperatures. The alloys grow epitaxially in t he hexagonal compact structure with a columnar microstructure. Some lo ng range order, corresponding to a concentration modulation along the growth axis, has been observed in the layers deposited at Low temperat ure (T < 750 K). At the higher temperature (T = 820 K) the diffusion o f the buffer layer Ru in the edges of the columns isolates them magnet ically and is responsible of the large coercitive field (approximate t o 3 kOe) measured in the polar geometry for the sample prepared at the higher (T = 820 K) deposition temperature.