Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Skyrmions and effective model of the resistive electron quadrupling
  state   Recent experiments [Grinenko $\textit{et
al.}~\href{http://doi.org/10.1038/s41567-021-01350-9}{\text{Nature
Physics}~\textbf{17},~1254\!-\!1259~(2021)}$] reported the observation of a
condensate of four-fermion composites. This is a resistive state that
spontaneously breaks the time-reversal symmetry, leading to unconventional
magnetic properties, detected in muon spin rotation experiments and by the
appearance of a spontaneous Nernst effect. In this work, we derive an effective
model that describes the observed spontaneous magnetic fields in this state. We
show that this model, which is alike to the Faddeev-Skyrme model for the
four-fermion order parameter, hosts skyrmions: magnetic-flux-carrying
topological excitations.

28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
1
The categories of this paper are: cs