Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 14: Surface Magnetism – Skyrmions (jointly with MA, O)

TT 14.12: Vortrag

Montag, 16. März 2015, 12:30–12:45, EB 301

Tailoring a Spin Spiral by Uniaxial Strain — •Pin-Jui Hsu, Aurore Finco, Lorenz Schmidt, Andre Kubetzka, Kirsten von Bergmann, and Roland Wiesendanger — Department of Physics, Hamburg Univerisyt, 20355 Hamburg, Germany

Spin spirals typically result from competing magnetic interactions. In the presence of a sizable Dzyaloshinskii-Moriya (DM) interaction, the spin spirals exhibit a unique rotational sense and their periodicity is governed by the ratio of the exchange and DM-interaction strength. Spin-polarized scanning tunneling microscopy (SP-STM) experiments have already revealed several examples of cycloidal and conical spin spiral states in ultrathin films of magnetic transition metals (e.g. Fe, Mn, Cr) on heavy-element substrates (e.g. W, Ir). Here, we report on a SP-STM study on two monolayers of Fe on Ir(111) where a regular dislocation line structure with a periodicity of 3.71±0.47 nm is observed due to the strain relief of bcc(110) Fe grown epitaxially on the Ir(111) substrate. SP-STM reveals the presence of cycloidal spin spirals with a period of 1.82±0.15 nm which are guided by the dislocation lines to form a well-defined spin-ordered state. These ordered spin spirals form an undulating pattern perpendicular to the dislocation lines wiggling with an angle of about 155^o, indicating an interaction between structural relaxation and the observed spin structure, particularly along the three symmetrically equivalent crystallographic axes. In contrast, a disordered spin spiral state, which locally exhibits a period of 1.38±0.22 nm is observed in the regions without dislocation lines.