Local atomic structure of ultrathin Fe films grown on Cu(100)

A. Biedermann, R. Tscheließnig, M. Schmid, P. Varga

Institut für Allgemeine Physik, Technische Universität Wien, 1040 Wien, Austria

Appl. Phys. A 78 (2004) 807-816

Ultra-thin epitaxial Fe films grown by thermal deposition on Cu(100) are analyzed by scanning tunneling microscopy. Evidence is presented that the morphological characteristics and magnetic properties are a direct consequence of fcc-to-bcc transitions reminiscent of those occurring in bulk Fe. In contrast to the assumption of a ferromagnetic fcc phase in previous models of the Fe/Cu(100) system, we observe a tightly twinned and strained bcc-like phase termed nanomartensite in films below 5 ML thickness, which encompasses almost the entire film volume of 3 ML films. In addition, the surface of 7-8 ML films reconstructs by forming non-close-packed structures with bcc-like bond angles. The formation of these bcc-like phases is the reason for the expansion of the interlayer spacing observed in these films and correlates perfectly with their ferromagnetic ordering.

Corresponding author: M. Schmid (schmid< encoded email address >).

Users with online access to Applied Physics A can load the article from the publisher.