Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 14: Surface Magnetism – Skyrmions (jointly with MA, O)
TT 14.12: Talk
Monday, March 16, 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 155o, 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.