Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Skyrmion and Tetarton Lattices in Twisted Bilayer Graphene   Recent experiments on twisted bilayer graphene show an anomalous quantum Hall
(AQH) effect at filling of $3$ electrons per moir\`e unit cell. The AQH effect
arises in an insulating state with both valley- and ferromagnetic order. We
argue, that weak doping of such a system leads to the formation of a novel
topological spin texture, a `double-tetarton lattice'. The building block of
this lattice, the `double-tetarton', is a spin configuration which covers $1/4$
of the unit-sphere twice. In contrast to skyrmion lattices, the net
magnetization of this magnetic texture vanishes. Only at large magnetic fields
more conventional skyrmion lattices are recovered. But even for large fields
the addition of a single charge to the ferromagnetic AQH state flips hundreds
of spins. Our analysis is based on the investigation of an effective non-linear
sigma model which includes the effects of long-ranged Coulomb interactions.

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The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin