Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pinning and hysteresis in the field dependent diameter evolution of
  skyrmions in Pt/Co/Ir superlattice stacks   We have imaged N\'eel skyrmion bubbles in perpendicularly magnetised
polycrystalline multilayers patterned into 1 \mu m diameter dots, using
scanning transmission x-ray microscopy. The skyrmion bubbles can be nucleated
by the application of an external magnetic field and are stable at zero field
with a diameter of 260 nm. Applying an out of plane field that opposes the
magnetisation of the skyrmion bubble core moment applies pressure to the bubble
and gradually compresses it to a diameter of approximately 100 nm. On removing
the field the skyrmion bubble returns to its original diameter via a hysteretic
pathway where most of the expansion occurs in a single abrupt step. This
contradicts analytical models of homogeneous materials in which the skyrmion
compression and expansion are reversible. Micromagnetic simulations
incorporating disorder can explain this behaviour using an effective thickness
modulation between 10 nm grains.

29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ