Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 115: Metallic Nanowires on the Atomic Scale (jointly with DS, O)
TT 115.6: Talk
Friday, March 20, 2015, 11:00–11:15, H 2032
Tuning the Playground for Spin-Polarization in Au-Induced Atom Chains on High-Index Silicon Surfaces — •Julian Aulbach1, Joerg Schaefer1, Steven C. Erwin2, and Ralph Claessen1 — 1Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Germany — 2Naval Research Laboratory, Washington DC, USA
Atomic wires on semiconductor substrates allow direct access to spectroscopic studies of the low-temperature ground state of quasi-one-dimensional systems, such as a charge density wave or a Tomonaga-Luttinger liquid. A particularly intriguing concept is the use of high-index silicon surfaces of the type Si(hhk), providing tunability with respect to terrace width and adatom coverage. As a specific representative, stabilization of the Si(553) surface by Au adsorption results in two different atomically defined chain types, one made of Au atoms and one of Si. The latter, situated at the step edges, forms a honeycomb nanoribbon. At low temperature these silicene-like ribbons develop a period tripling, previously attributed to a Peierls instability. Here we report evidence from scanning tunneling microscopy that rules out this interpretation [1]. On the contrary, our results are in excellent agreement with density functional calculations [2], which reveal an antiferromagnetic ordered state, where every third Si atom at the step edge hosts a single electron [1]. Additionally we will also address the consequences for this spin ordering by varying the high index substrate.
[1] J. Aulbach et al., Phys. Rev. Lett. 111, 137203 (2013).
[2] S. C. Erwin and F. J. Himpsel, Nature Commun. 1, 58 (2010).