Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pressure Induced Stripe-order Antiferromagnetism and First-order Phase
  Transition in FeSe   To elucidate the magnetic structure and the origin of the nematicity in FeSe,
we perform a high-pressure $^{77}$Se NMR study on FeSe single crystals. We find
a suppression of the structural transition temperature with pressure up to
about 2 GPa from the anisotropy of the Knight shift. Above 2 GPa, a
stripe-order antiferromagnetism that breaks the spatial four-fold rotational
symmetry is determined by the NMR spectra under different field orientations
and with temperatures down to 50 mK. The magnetic phase transition is revealed
to be first-order type, implying the existence of a concomitant structural
transition via a spin-lattice coupling. Stripe-type spin fluctuations are
observed at high temperatures, and remain strong with pressure. These results
provide clear evidences for strong coupling between nematicity and magnetism in
FeSe, and therefore support a universal scenario of magnetic driven nematicity
in iron-based superconductors.

3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph