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O: Oberflächenphysik

O 4: Epitaxie und Wachstum I

O 4.8: Vortrag

Freitag, 4. März 2005, 12:30–12:45, TU EB202

Bcc-like crystal structures in ultrathin "fcc" Fe films on Cu(111) — •Albert Biedermann, Werner Rupp, Michael Schmid, and Peter Varga — Institut für Allgemeine Physik, Vienna University of Technology, 1040 Vienna, Austria

Growing ultrathin Fe films on fcc substrates can stabilize the fcc structure of Fe. More often, however, distorted bcc-like structures are found instead. Fe/Cu(100) films are very flat and show relatively well defined fcc and bcc-like phases, among them a "nanomartensitic" bcc-like phase [1]. In contrast, Fe/Cu(111) films grown by thermal deposition are relatively rough, favoring Cu surface segregation and hampering standard LEED-I/V analyses. We have used atomically resolved STM and STS of clean and H-covered bi- and multi-layer islands together with XPD data by Kief and Egelhoff [2] to show the presence and conditions of stability of strained bcc-like phases in Fe/Cu(111) films. Our results are compared to published magnetic measurements [3] and first principles predictions [4], which favor an ideal fcc phase for very thin films.

[1] A. Biedermann, R. Tscheließnig, M. Schmid, and P. Varga, Appl. Phys. A 78 (2004) 807.

[2] M. T. Kief, W. F. Egelhoff, Jr, Phys. Rev. B 47 (1993) 10785

[3] P. Ohresser, J. Shen, J. Barthel, M. Zheng, C. V. Mohan, M. Klaua, and J. Kirschner, Phys. Rev. B 59, 3696 (1999).

[4] Spišák and J. Hafner, PRB 67 (2003) 134434