SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 25: Poster Session II: Surface magnetism II
O 25.7: Poster
Montag, 1. März 2021, 13:30–15:30, P
Spin-spiral state of a Mn monolayer on W(110) at variable temperatures as seen by x-ray absorption spectroscopy — •Ondrej Sipr1, Kirsten von Bergmann2, Hubert Ebert3, Roland Wiesendanger2, and Jan Honolka1 — 1Institute of Physics, Czech Academy of Sciences, Praha — 2University of Hamburg, Germany — 3Ludwig-Maximilians-Universität München, Germany
The noncollinear magnetic state of epitaxial Mn monolayers on tungsten (110) crystal surfaces is investigated by means of soft x-ray absorption spectroscopy, to complement earlier spin-polarized STM experiments. X-ray absorption spectra (XAS), x-ray linear dichroism (XLD) and x-ray magnetic circular dichroism (XMCD) Mn L2,3-edge spectra were measured in the temperature range from 8 to 300 K and compared to results of fully-relativistic ab initio calculations. We show that antiferromagnetic (AFM) helical and cycloidal spirals give rise to significantly different Mn L2,3-edge XLD signals, enabling thus to distinguish between them.
It follows from our results that the magnetic ground state of a Mn monolayer on W(110) is an AFM cycloidal spin spiral. Based on temperature-dependent XAS, XLD and field-induced XMCD spectra we deduce that magnetic properties of the Mn monolayer on W(110) vary with temperature, but this variation lacks a clear indication of a phase transition in the investigated temperature range up to 300 K — even though a crossover exists around 170 K in the temperature dependence of XAS branching ratios and in XLD profiles.