Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin-polarized scanning tunneling microscopy characteristics of
  skyrmionic spin structures exhibiting various topologies   The correct identification of topological magnetic objects in experiments is
an important issue. In the present work we report on the characterization of
metastable skyrmionic spin structures with various topological charges
($Q=-3,-2,-1,0,+1,+2$) in the (Pt$_{1-x}$Ir$_{x}$)Fe/Pd(111) ultrathin magnetic
film by performing spin-polarized scanning tunneling microscopy (SP-STM)
calculations. We find that an out-of-plane magnetized tip already results in
distinguished SP-STM contrasts for the different skyrmionic structures
corresponding to their symmetries. Our work also establishes an understanding
of the relationship between in-plane SP-STM contrasts and skyrmionic topologies
through an investigation of the variation of the in-plane angle between the
spins along the perimeter of the structures, which can be characterized by the
local vorticity or linear density of the winding number. For spin structures
exhibiting a uniform sign of the local vorticity throughout the whole
skyrmionic area, we demonstrate that (i) $|Q|$ can be determined from a single
SP-STM image taken by any in-plane magnetized tip, and (ii) an in-plane tip
magnetization rotation provides the sign of $Q$ independently of the sign of
the effective spin polarization in the tunnel junction. We also discuss cases
where the local vorticity is changing sign. Finally, by increasing the Ir
content of the PtIr overlayer, we find an appearing secondary outer ring
in-plane SP-STM contrast that is indicative of attractive skyrmions or
antiskyrmions.

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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: physics