Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 71: Surface Magnetism (jointly with MA)

O 71.2: Vortrag

Donnerstag, 14. März 2013, 15:30–15:45, H3

Large wave vector surface spin waves of the nanomartensitic phase in ultrathin iron films on Cu(100) and fcc Co(100) — •Rajeswari Jayaraman, Harald Ibach, and Claus M. Schneider — Peter Grünberg Insitut, Forschungszentrum Jülich, 52425 Jülich, Germany

It is generally accepted that thin-film magnetism is strongly affected by even small structural modifications. Much less is known about the influence of structure on magnetic excitations, in particular, spin waves. Using electron energy loss spectroscopy we have studied the dispersion of large wave vector surface spin waves of a system for which details of the structure became known only recently, namely ultrathin iron films grown on Cu(100) surfaces. We find the spin wave dispersion to be nearly identical to the dispersion reported for bcc Fe(110) layers grown on W(110). We therefore conclude that the spin wave signal stems from the "nanomartensitic" phase of Fe/Cu(100) and that this phase is not merely a surface phase but encompasses the deeper layers. The same spin wave dispersion and LEED pattern as for the Fe/Cu(100) system is observed when Fe is deposited on fcc Co(100)/Cu(100). We therefore conclude that these Fe films likewise assume the nanomartensite structure.