fcc-bcc phase transition of epitaxial Fe/Cu(111) films: a structural and magnetic study

Epitaxial Cu/Fe/Cu trilayers with Fe film thickness between 4 and 110 Angst rom have been deposited on the 7 x 7 reconstructed surface of Si(111) singl e crystal. The structural and chemical characterization of Fe films was acc omplished by in situ low energy electron diffraction, Kikuchi electron diff raction and Auger electron spectroscopy. As the Fe thickness exceeds about 6-8 Angstrom. a fcc-bcc phase transition occurs by the appearance of bcc(11 0) domains in the Kurdjumov-Sachs orientation. The structural transformatio n is also confirmed by ex situ X-ray diffraction experiments in the theta-2 theta configuration. The evolution of the magnetic properties with the Fe film thickness has been studied by means of surface magneto-optic Kerr effe ct. Hysteresis loops measurements in the longitudinal configuration show a marked increase of the saturation signal which can be associated with the s tructural fcc-bce phase transition of Fe. (C) 1999 Elsevier Science B.V. Al l rights reserved.